I forgot my pass code, how to change it?

OS X: Changing or resetting an account password

Forgot Mac Password? How to Reset Your Mac Password (with or without CD)

Change the Admin Password with Mac OS X Single User Mode

Reset mac mini admin password: Apple Support Communities

This is the MacPro desktop computer forum

If you

Forgotten Screen-Lock Passcode for iPod touch, iPad or iPhone

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

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.