No sound leads me to believe it may be a fuse, so check that first. Otherwise, depending on how old it is, it is probably the motor itself. $50 for a used motor and about an hour of labor and you should have a working sunroof.
Everyone of my 6 previous 4Runners had no issues. So I never bothered to look into it. If the motor is a common issue I'm fine with swapping it. Just didn't want to buy one if there is something else that is a common issue.
I noticed mine stopped working today, it goes to open but then immediately dies and the motor stops, im guessing the motor is dead? have you looked into the problem yet? im not really worried about it right now as winter is coming and i have other things that need to be done to the vehicle but id like to have it fixed