[LAU] What have I done now??

I just notice last night that sometime during my adventures in Linuxsampler I've managed to break amarok, which has always been solid. Now, it seems that amarok won't play .m4a file. I have a HUGE songlist, and it's always played whatever was in the songlist, but not now! I'm obviously overwritten something while I was installing packages, but I have no idea what file I'm looking for. Does anyone here have ANY idea off the top of your collective head how I get amarok back to the way it used to be? Thanks. I think once I get that fixed, I'm done trying to install things. The only thing I've ultimately managed to do is break amarok. Thanks to everyone.