Need help on my itouch

Hello, i got a problem... like my ipod, my itouch has just deleted all my music after synchronising and i need help as to why this has happened. Before i lost everything i tried to synchorise it and it came up with some form of warning so i believed it was because i was doing something on it during its synchronising process so when i plugged it back in, thats when i lost everything. I got the "manually manage music and videos" ticked aswell. Could this be a fault with my itunes or do i need to update it? Or could it be something wrong with my itouch? I only got it in May aswell. Anyway, help would be appreciated thanks.