I have rewound a bobbin on my sewpro sewing machine. When I loaded the bobbin back in the machine I can't get the machine to pick up the thread to sew again.

What size needle are you using. Maybe a larger size will help.

Not quite sure since the symptoms are not clear. "Bumpy stitches from bobbin"--does that mean there were thread nests on the bobbin side of the fabric? That is thread nesting or bird nesting resulting usually from mis-threading, upper thread not completely seated in tension disk, or upper tension too loose. Remove the upper thread from the machine. ALWAYS RAISE the presser foot and rethread from the beginning--verify the thread path is correct. Set the upper tension to the midway point between high & low number and retest the machine. (Upper tension may need to be tweaked because fabric, thread, and age of the machine will have an affect.)

Check that the bobbin is wound smoothly--no lumps, bumps, or thread ends/pieces sticking out of the bobbin. Check that the bobbin is installed in the bobbin case correctly (turning the proper direction) and the bobbin tension is threaded completely.

If the upper thread is not picking up the bobbin thread, make sure to install a brand new needle. (I don't try to straighten or "fix" damaged needles. With today's computerized machines, it may cause more damage than a new needle would cost. That may work on the old mechanical machines like the Singer Featherweights, but my machines are too important to risk for the price of a needle.) If it still won't pick up the bobbin thread, then the machine's timing has probably been knocked out of alignment. Search for sewing machine timing or take it for service.

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Remove the thread from the machine. (Always raise the presser foot and pull the thread up, NEVER down!).
Install a brand new needle.
ALWAYS RAISE the presser foot when threading.
Rethread from the beginning and verify the thread pathway is correct.
Set the upper tension to midway between High & Low numbers--you may need to tweak this for your particular machine, but this is a standard starting point.
Confirm the bobbin is loaded and threaded correctly in the bobbin case.
Begin sewing slowly. It helps if you begin sewing with the needle in the uppermost position.
Test on medium weight woven cotton.

If it is still not picking up the bobbin thread, then it most likely is a timing problem. You can search the internet for web sites and videos regarding sewing machine timing or take it for service.

Sewing Machine Thread Bunching Up Here Why

Birds nest under the fabric big loops of thread top side looks good...

What causes Bird Nests Superior Threads

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If by "won't stitch" you mean that the top thread will not pick up the bottom thread, make sure you have the needle threaded properly. If the machine is a top loading bobbin, the thread goes in the needle from front to back. Same if it's a side loading bobbin (bobbin faces you as you sew). If it's a front loading bobbin (bobbin faces left of machine), the thread goes in the needle from left to right.

Sounds like the timing isn't quite right. Your best bet is to go have it serviced and timed.

try changing the needle
rethread the machine top and bobbin
make sure to use every thread guide
make sure the top thread has not come off the thread take up
lever--this can cause the sewing machine to jam
if it's a top loading bobbin--take the bobbin out of the bobbin case
and turn it around and reinsert the bobbin
if it's a side or front loading bobbin take the bobbin and bobbin
case out and make sure the bobbin is inserted correctly into the
bobbin case and that the bobbin case is inserted correctly into the
sewing machine.

You can view and/or download a manual at the Brother Website - http://www.brother-usa.com/manuals/default.aspx?PGID=3&R3ModelID=CE4000

Go here http://www.topinnovations.com/sewpro/archived/SP-402/pdf/SP-402_Manual.pdf

It looks right but its not. Try looking on the internet for threading instructions. The bobbin winds in two directions, I have never saw a Bernina but I have 2 new machines and the thread goes in and then threads back to the left. Its hard to describe. But if the bobbin isn't right it will not pick up the thread. Write to Bernina for instructions. There are websites that have the directions for free.

Try changing your needle