iphone 4 music player problem

Need some help please, no idea where to start.

My mum has the iphone 4. I've no idea what she was doing but I think she was trying to link her phone to the icloud or something. Anyway, it deleted almost all of the music from her phone.

I say almost all, there are 5 songs left out of a few hundred. The music app seems to be constantly running and skipping through these 5 songs. Doesn't actually play them, one song comes on the screen with no sound then after a second it skips to the next and keeps doing this in a loop. I have no idea how to stop it!

Has anyone any experience with this? I had the SIII and have no knowledge of iphones, I am technically aware though.

Cheers