Q: how restore passcode on ipod touch

Forgotten Screen-Lock Passcode

Connect the iOS device to your computer and try to make a backup

iOS: How to back up

https://support.apple.com/en-us/HT203977

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

https://support.apple.com/en-us/HT201263

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

https://geekindisguise.wordpress.com/2009/07/16/how-to-put-ipod-touch-iphone-int o-dfu-mode/

For how to restore:

iTunes: Restoring iOS software

https://support.apple.com/en-us/HT201252

To restore from backup see:

Restore your device from an iCloud or iTunes backup - Apple Support

https://support.apple.com/en-us/HT204184

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   

https://support.apple.com/en-us/HT201272

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.