When I select a song on my device, a different song plays and then album cover is wrong.

Try:

- Reset the iOS device. Nothing will be lost

Reset iOS device: Hold down the On/Off button and the Home button at the same time for at

least ten seconds, until the Apple logo appears.

- Unsync/delete all music and resync

To delete all music go to Settings>General>Usage>Storage>Manage Storage>Music>Tap edit in upper right and then tap the minus sign by All Music

- 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. See:

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

- Restore to factory settings/new iOS device.

and:

http://www.mcelhearn.com/deleting-the-itunes-album-artwork-cache-folder-may-reso lve-problems-with-album-art-displaying/