Quote Originally Posted by Pseudojazzer View Post
I will try tomorrow to reinstall and use the backup...
Yes run a backup before you reinstall (make sure it arrives in email before you proceed) but this is just a precaution because your songs are stored in your user area not within the app itself. Delete the app then download again (you are not charged if you are logged into the same iTunes account that purchased it). The songs are automatically loaded so when you open all should be there.