Try:
- Reset the iPod. Nothing will be lost
Reset iPod touch: Hold down the On/Off button and the Home button at the same time for at
least ten seconds, until the Apple logo appears.
- Reset all settings
Go to Settings > General > Reset and tap Reset All Settings.
All your preferences and settings are reset. Information (such as contacts and calendars) and media (such as songs and videos) aren’t affected.
- Restore from backup
- Restore to factory settings/new iPod.
- Make an appointment at the Genius Bar of an Apple store.
Apple Retail Store - Genius Bar
The Reset All Settings frequently works for your problem