Check that you are getting power to the sunroof motor. Go to the trunk/back cargo area?? (Don't all wagons have manual sunroof?)

find the motor and use one of those 12V testers and see if you get power to the motor when you activate the switch.
You could unplug it (it has a two-pin connector)

If there is power then it's probably the motor or the sunroof is stuck or something.

See if you can operate it manually using the emergency sunroof nut

If you don't have current to the motor.
There should be a fuse guide in the fuse box telling you which one is associated with which electrical part(s)

replace as necessary. If you don't have the fuse just take one out from another that is similar in rating. (same color) - Remember to replace it back though..

If that doesn't help check out the switch in the center console. Pry it out and clean it out with electrical cleaner of some sort. If that doesn't help.. replace the switch (find used or something)

I have not done this myself but that's what I would do
good luck

__________________
2008 BMW 335i Coupe