Lockscreen wallpaper replaced with music screen background ??

[talk nerdy to me]

I was listening to the music files I've downloaded and now my lockscreen wallpaper has been replaced with a screen similar to that when you go to listen to your music files. I have no idea what I did that caused this change and I've tried to go back and reassign my lockscreen wallpaper but to no avail.

Any ideas??

Thanks!