why all my songs do not show on my ipod but shows in itune when connected to itune?

Have you tried resetting the iPod to see if that does any good? To do this, press and hold both the Select/Center and Menu buttons together long enough for the Apple logo to appear.

Perhaps it's a drive letter conflict.

Windows confuses iPod with network drive or hard drive and may keep iPod from mounting or songs may seem to disappear

Otherwise, something was corrupted during the sync process, in which case you'll need to restore the iPod to factory settings in iTunes and resync everything back over to it.

B-rock