Can you help me with my ipod touch 2g problems?

I jailbroke my ipod 2 days ago because my warranty was up anyway. I did something where the ipod had to be resprung, and it never came back on! I reset it and the apple symbol shows up. It will never go to the home screen.I plugged it in and itunes recognizes the ipod but it cant back it up or anything.How can I get it back to normal? twice I could see my home screen for about a millisecond and then back to the apple symbol. The load sign is up too but it freezes sometimes. Did I ruin my ipod!?!?!? please help and youll get 10 pts