Katey,
I had the same problem last year! My sunroof just wouldnt do anything!
Unfortunately, it broke while it was open, so I looked at the manual and it tells you how to close it manually. I then took it to a Fiat garage where they found the motor was broken. They fitted a replacement motor and it has worked fine ever since.
As for the cost, they said it was £300, but the car was still under warranty...phew!
Hope this helps!
Tim