Does your sunroof leak?? If so then there is probably some water in the motor so it might have packed up.
You can open it manually, if you take off the plastic thingy (technical word) where the sunroof switch is housed then you will be ably to see the motor and on the bottom of that is a hole for an allen key. Find the right size and some superhuman strength and you can open the sunroof by turning the allen key. This might free it up as it might just be stiff/stuck.
Oh and try drying the switch out if the sunroof leaks as if could also be this.
Hope it helps, Phil