ipod syncs but doesnt update new songs from the library to the ipod

I had problems syncing my ipod touch, a message appeared on the computer, which said the itunes program was corrupted/damaged so it advised to reinstall itunes, which i did. This wiped my library from the computer. When i connected the ipod to the computer it said it is was syncing, but no data got transfered either from the ipod to the computer or visa versa. My ipod still retains its songs/apps etc.