Updating iPod, erases music?

[cyphercide]

Yeh already done. everything washed from ipod. now I have copied the saved music files to ipod from laptop but these are not synchronized somehow on the ipod.

now how to get these on ipod. it has only synchronized three songs that too from apple store

Unlike regular MP3 players, an iPod can only interface with and reflect a single iTunes playlist. The probable reasons why you faced your initial "restore" issue:

You are using a different system from the one you first set up your iPod with.

You reinstalled iTunes on your system.

In order for your old songs to show up on your iPod, you need to first add them to your current(iTunes) playlist. Open iTunes and use the "Add file to library " option to select the songs you wish to have on your iPod. Once you are done with that, connect your iPod and use the "Sync" button to update your iPod playlist accordingly.

And you might find the iCloud services very helpful if you routinely change your PC.