Forgot password

If it has not been backed up and the passcode is forgotten there is nothing that can be done about loss of data. To remove the passcode you have to place the iPod in recovery mode: http://support.apple.com/kb/HT1212 which will erase all content.

Forgotten Screen-Lock Passcode

Connect the iOS device to your computer and try to make a backup. You should be able to backup if your previously synced to this computer and the screen does not say connect to iTunes

iOS: How to back up

Then restore via iTunes. The iOS device will be erased. Place the iOS device in Recovery Mode if necessary to allow the restore.

If recovery mode does not work try DFU mode.

How to put iPod touch / iPhone into DFU mode « Karthik's scribblings

For how to restore:

iTunes: Restoring iOS software

To restore from backup see:

iOS: Back up and restore your iOS device with iCloud or iTunes

If you restore from iCloud backup the apps will be automatically downloaded. If you restore from iTunes backup the apps and music have to be in the iTunes library since synced media like apps and music are not included in the backup of the iOS device that iTunes makes.

You can redownload most iTunes purchases by:

Downloading past purchases from the App Store, iBookstore, and iTunes Store

If problem what happens or does not happen and when in the instructions? When you successfully get the iPod in recovery mode and connect to computer iTunes should say it found an iPod in recovery mode.