my iPod classic doesn't complete syncing to iTunes, it starts but at the end it shows a message saying that it cannot be synced. Please help me!!!!

If you have not already, you may want to do a Restore in the iPod using iTunes. This erases the iPod, reinstalls its software, and sets it to default settings.

Use iTunes on your Mac or PC to restore your iPhone, iPad, or iPod to factory settings - Apple Support

If the problem is only data corruption, the Restore should resolve it. If the problem recurs after doing a Restore, the iPod may have a hardware problem, such as a faulty hard drive.