20GB is taken up by other
I have a 32GB Ipod Touch and "other is taking up 90% of the storage. why?
An "other" larger than about 1 1/2 GB indicates corrupted files.
What is the Other on my iPhone and How to Remove It
What is "Other" and What Can I Do About It?
Next, usually restoring from backup eliminated the corrupted files. However, sometimes restoring to factory settings/new iPod is required.
To restore from backup see:
To restore to factory settings/new iPod see: