Yale deadbolt nigtlatch works only with key

You likely have the lever that goes from the outside portion of the lock through the striker/bolt assembly into the inside portion rotated into an incorrect position when you insert it into the striker/bolt assembly.

I noticed last time I changed locks if I tightened the 2door knob pieces to much I couldn't use lock at all.loosened just all and works no problem

I presume you figured it out by now, but if the tailpiece is installed wrong in many deadbolts, the key won't come out in one position or the other. It's called a "timing" problem and the way to fix it is to take it off the door, turn the tailpiece a half circle and put it back on the door. Usually Kwikset locks are designed so you can't put it in the wrong way, but it can happen. (If it's not the timing problem, then the deadbolt unit is defective or broken. They are designed to fail in a way that keeps them locked, so this could be a sign that someone tried to break in, or that someone used the extended bolt as a way to stop the door from closing and it hit the door frame too hard.)

The best way to install a deadbolt lock without the instructions handy is to look at the "lazy" cam and see if there is a way to install it wrong and don't install it that way. Example: If there are 2 ways for the tailpiece to fit in the deadbolt unit when the deadbolt is retracted and only one way for the tailpiece to fit in when the deadbolt is extended, then install the lock with the deadbolt extended and you can't install it wrong.

Assuming this is a 'yale' type latch key lock.
Unscrew the lock assembly from the inside of the door. Behind it you will gain access to fixing screws for exterior assembly - just tighten them up.

my guess is that during installation the inside lock cylinders were 1/2 or a full rotation more in one direction than the outside cylinders. remove it from the door, assemble it and try it without installing it. If it doesn;'t work, take it back. If it's old, oil it. if that doesn't work- toss it- you've spent an hour on a $15 item.

it sounds as though the linkage that pulls the deadbolt back has disengaged... if you undo the screws from the inside of the door and remove the manual knob there will be 2 more screws holding the key lock to the door. A thin flat bar is attached to the key lock that goes through the deadbolt and into the manual knob. This bar turns with the key, sliding the bolt on its track to lock and unlock the door. Once the lock is apart check the key in the lock to see if the bar turns when the key does. then see if there is anything that may be obstructing the deadbolt from sliding. The locks are pretty indestructible so if there is a problem it may have been from the install... perhaps the door is to wide for the lock to engage properly and the lock worked loose in the 6 months that it worked.

It sounds like the exterior tumbler is bad, it is less expensive to just replace the whole deadbolt than to have the tumbler repaired.

This must be cut and drilled out unless you gret a locksmith to pick the lock open by manipulation

You are 180 degreees out of sync with the other side of the bolt. Take it apart and move your key 180 degrees and reassemble and try it. Im 51% sure this is your trouble

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a

if you remove the screw from the deadbolt and remove the keyed parts you can see the plunger assembly. you can use a flat head screw driver and turn the plunger in. it will unlock the door and you will be able to replace the deadbolt