The first thing you need to do is find out what check(s) bounced, the bank can tell you this. The bank should also give you the bounced check back which can be redeposited at least one more time.
I would redeposit the check, then call the book and tell them if it bounces again you're going to post this info on every gambling forum you can find.
In the meantime, cover your negative because not doing such can really fuck your credit up and make it hard for you to open new bank accounts. If it goes negative for something like 15 days, the bank will usually close your account and report it to ChexSystems, then your problems begin.