my ipod touch's camera stopped working..how can i fix it?

How old is it?

You may want to try a software restore or walk it into the nearest Apple Store and ask for assistance there.

how do u do the software resore

First try restoring from backup.I

If still problem. restore to factory defaults/new iPod

See the restoring topic of the following fro how:

iTunes: Backing up, updating, and restoring your iPhone, iPad, or iPod touch software