Lost all downloaded songs

[Peterson41]

I was using it as usual, and after a few hours when I next opened the app, the log in screen appeared. I logged in but the app now shows that I don't have any downloaded songs. I do not have any other accounts, this is the only one I use. Also, the music files are in fact still on my sd card but the app doesen't notice them.
There is no way to download all that 20+ gigs of music for this whole week. Is there any way to save my music?