How to repair/restore ipod and recover the songs?

Itunes says my ipod nano is corrupted and needs to be restored.Tried restoration as said in Apple forum and tutorials but none of them worked. I also cannot open ipod files through My computer and it is not recognised by Itunes after I connect it to the computer's usb port. I cannot restore because of error 1415. OS is windows vista. On the ipod settings, there is only 1.1 GB free of 80 GB but cannot access the songs because the ipod displays that it doesn't have any songs. Tried using some apps which promised to repair and restore ipod but they did 't work. Desperately need help!!