I bent my sewing machine and tried to replace it, but the needle is stuck in the machine even though the clamp is all the way out. I tried pulling the needle with pliers but it won't move.

I'd need to know what type of machine you have, but maybe you aren't putting the clamp on correctly. They are fussy! Be sure you have the flat side of the needle facing the correct way and that you wiggle and jiggle it while pushing up on the needle. Also, make sure you are using a new needle and not the old bent one. Sometimes the clamp will come in 2 pieces, so it may not have broken, just came undone.

Here is what I found Hope it helps. I didn't download anything, I just clicked on the pages and scrolled down. Here is the contents page

http://homeappliance.manualsonline.com/manuals/mfg/brother/cs770.html?p=5

Here is the page you need:
http://homeappliance.manualsonline.com/manuals/mfg/brother/cs770.html?p=23

21
1
Checking the needle
Sewing with a bent needle is extremely dangerous since the needle may break while the machine is being operated.
Before using the needle, place the flat side of the needle on a flat surface and check that the distance between the needle and the flat surface is even.
aFlat side
bNeedle type marking
?Correct needle
aFlat surface
?Incorrect needle
If the distance between the needle and the flat surface is not even, the needle is bent. Do not use a bent needle.
aFlat surface
Replacing the needle
Replace the needle as described below. Use the screwdriver and a needle that has been determined to be straight according to the instructions in "Checking the needle" .
a
Raise the needle by turning the handwheel toward you (counterclockwise) so that the mark on the wheel points up. (With models equipped with (needle position button), raise the needle by pressing once or twice.)
b
Turn off the sewing machine.
c
Lower the presser foot lever.
aPresser foot lever

Is the bobbin winder on? If so, turn it off.
Otherwise, is there power to the machine?
And this happened while you were sewing? Cut the thread above the needle eye. Rock the handwheel back and forth firmly to try to cut the thread jam below the needle plate with the sewing hook. If that doesn't work, open the bobbin case area of the machine and try to pull the bobbin case out, cutting any threads you can see with a seam ripper. Still won't come? Take the needle out of the needle clamp and throw it away (it's bent!), and take the screws out of the needle plate (=throat plate) and take the needle plate off after cutting any threads you can reach under the fabric. Keep cutting and pulling out any thread you find, and eventually, you'll be able to turn the handwheel. Clean all the thread bits, lint, and junk out of the area under the needle plate, the bobbin and bobbin case, and the shuttle area... there will be directions in your manual on how to clean the machine, including the shuttle area. Reassemble. Put in a brand new needle, right way around and fully up in the needle clamp. Rethread from scratch.
Always hold the thread ends behind the presser foot for the first couple of stitches of each seam.

See also: http://www.picturetrail.com/sfx/album/view/22521551

try undoing the lock screw fully and gently move the clamp in the opposite direction the the lock screw, it should drop off.

Upper thread breaks
1.the needle may be bent or damaged--try rolling the needle on a flat surface to see if it's bent or not
Or the needle could be in backwards
Correct needle insertion
Correct needle insertion is mandatory for proper use of sewing machine.
Raise the needle bar to the highest point, then loosen the clamp screw to remove the old needle, place the new needle in the clamp with the flat side to the back of the machine or if using a round needle--the groove in the needle should face away from the shaft.
Push the needle all the way up to the stop or as far as it will go, then tighten the needle clamp screw
2.upper tension may be to tight--try 3 to 5
3.thread may be hanging up in bobbin case--check area for loose threads or lint
???
Lower thread breaks
The most probable cause of lower thread breaking is improperly wound bobbin
1.always start with a empty bobbin
Never wind one color over the other
2.choose thread that is identical in color & type as the one to be used for upper threading
3.wind the bobbin evenly across & in layers
4.don't wind the bobbin so full that it would be tight & hard to insert into bobbin case
5.bent bobbin--replace
6.lint built up in the bobbin case--frequent cleanings will eliminate this problem, the more often you use the sewing machine the more often it needs to be cleaned
7.thread catching on the bobbin spring or latch on bobbin case, check to see that the bobbin is inserted completely & correctly, & that you are using the right kind of bobbin

for the top & bobbin thread keep thread tails of 3 to 6 inches long pulled behind the needle before you start sewing

yes,sometimes the thread will get caught on the spool, you might think about getting a extra holder that sets behind the machine to hold those spool's that the thread get caught on, that's what I did.

Upper thread breaks
1.the needle may be bent or damaged--try rolling the needle on a flat surface to see if it's bent or not
Or the needle could be in backwards
Correct needle insertion
Correct needle insertion is mandatory for proper use of sewing machine.
Raise the needle bar to the highest point, then loosen the clamp screw to remove the old needle, place the new needle in the clamp with the flat side to the back of the machine or if using a round needle--the groove in the needle should face away from the shaft.
Push the needle all the way up to the stop or as far as it will go, then tighten the needle clamp screw
2.upper tension may be to tight--try 3 to 5
3.thread may be hanging up in bobbin case--check area for loose threads or lint
???
Lower thread breaks
The most probable cause of lower thread breaking is improperly wound bobbin
1.always start with a empty bobbin
Never wind one color over the other
2.choose thread that is identical in color & type as the one to be used for upper threading
3.wind the bobbin evenly across & in layers
4.don't wind the bobbin so full that it would be tight & hard to insert into bobbin case
5.bent bobbin--replace
6.lint built up in the bobbin case--frequent cleanings will eliminate this problem, the more often you use the sewing machine the more often it needs to be cleaned
7.thread catching on the bobbin spring or latch on bobbin case, check to see that the bobbin is inserted completely & correctly, & that you are using the right kind of bobbin .

have you tried a new needle?
the needle may be bent or damaged--try rolling the needle on a flat surface to see if it's bent or not
Or the needle could be in backwards
Correct needle insertion
Correct needle insertion is mandatory for proper use of sewing machine.
Raise the needle bar to the highest point, then loosen the clamp screw to remove the old needle, place the new needle in the clamp with the flat side to the back of the machine or if using a round needle--the groove in the needle should face away from the shaft.
Push the needle all the way up to the stop or as far as it will go, then tighten the needle clamp screw

2.upper tension may be to tight--try 3 to 5

3.thread may be hanging up in bobbin case--check area for loose threads or lint

4.also clean under the needle plate for lint & loose threads

check to see if the thread has come off the thread take up lever

Upper thread breaks
1.needle may be in backwards
Correct needle insertion
Correct needle insertion is mandatory for proper use of sewing machine.
Raise the needle bar to the highest point, then loosen the clamp screw to remove the old needle, place the new needle in the clamp with the flat side to the back of the machine or if using a round needle--the groove in the needle should face away from the shaft.
Push the needle all the way up to the stop or as far as it will go, then tighten the needle clamp screw
2.upper tension may be to tight--try 3 to 5
3.the needle may be bent or damaged--try rolling the needle on a flat surface to see if it's bent or not
4.thread may be hanging up in bobbin case--check area for loose threads or lint
???
Lower thread breaks
The most probable cause of lower thread breaking is improperly wound bobbin
1.always start with a empty bobbin
Never wind one color over the other
2.choose thread that is identical in color & type as the one to be used for upper threading
3.wind the bobbin evenly across & in layers
4.don't wind the bobbin so full that it would be tight & hard to insert into bobbin case
5.bent bobbin--replace
6.lint built up in the bobbin case--frequent cleanings will eliminate this problem, the more often you use the sewing machine the more often it needs to be cleaned
7.thread catching on the bobbin spring or latch on bobbin case, check to see that the bobbin is inserted completely & correctly, & that you are using the right kind of bobbin .

1.upper tension may be to tight--try 3 to 5

have you tried a new needle
2.the needle may be bent or damaged--try rolling the needle on a flat surface to see if it's bent or not
3.Correct needle insertion
Correct needle insertion is mandatory for proper use of sewing machine.
Raise the needle bar to the highest point, then loosen the clamp screw to remove the old needle, place the new needle in the clamp with the flat side to the back of the machine or if using a round needle--the groove in the needle should face away from the shaft.
Push the needle all the way up to the stop or as far as it will go, then tighten the needle clamp screw
4.also check to see if the thread has come off the thread take up lever

There is a set screw above the needle pin screw which tightens with an allen wrench--try that.