Please help, i touch quit downloading new apps.

my new itouch 16gb that was jail broken by that Z phone program is having issues. It worked great for a couple months then one day it quit downloading new apps and wont even download updates or get on youtube anymore?? My wireless router seems to be working fine and gives off great signal, and i still have 8GB free space. The itouch recognizes my router and will bring up installer menu but halfway threw downloading or updating the thing stops and goes back to home screen kinda like its crashing or something. Any ideas?? please help!!
also i lost my z phone program so if anyone has the link to it maybe i can update from there and fix my problem IDK. Thanks