iPhone 4 Cydia Problem

I accidentally downloaded iAcces for 3.1.2 on cydia, it rebooted my iPhone 4 and now my cydia is completely messed up. It opens fine, but if you press packages in manage, there are no packages. It's the same for Sources, I tried adding some sources but it gives me some error message and crashes Cydia. It can't search for anything. Is there a way to reinstall cydia or a way to fix this? I've downloaded lots of games from Installous but I'm not sure if it would still work if I restore and re-jailbreak. I'm running on the 4.2.1 Firmware. Please Help.