Hello,
I was just experiencing that lately. I thought I would never find motivation again. Just 1/2 hour ago, I noticed that once I tried to start working, I had "restless leg syndrome". I just concentrated on stopping it, and starting work, and once I did (with good music in my earphones), I was satisfied to make progress. Just the satisfaction of seeing good work being done in front of me kept me going for a little while.
Thanks for sharing this with us, it feels good to see that I'm not the only one going through such things.
BTW, here is what I'm listening to, maybe that helps (no idea what your tastes are, but who knows...):
http://8tracks.com/drownbynumbers/memorial
I had a "coding stint" a long time ago, where I developed something "for fun", it was a for someone I knew but they never used it. I've tried reproducing this process, because back then I coded the whole thing in one weekend, never really succeeded, but now I am doing stuff that will be used and more appreciated - and I am happy if I manage to pick up and maintain a proper rate.