Did the other windows stop working all at the same time?
Have you confirmed that the back windows don't work if you use the rear switches (ensure that the child protection switch isn't on).
If all of the other windows stopped working at the same time then I would go with there being an electrical failure somewhere. Check the fuses first.
Can you control the remaining window using the driver's door switch? If so then there is at least power to that switch pack.
When attempting to activate a window can you hear any noises from within the door? If so this would indicate a window regulator failure (this is a DIY job if you have some experience, a drill and a few other basic tools.) I wouldn't have expected 3 to have broken at the same time though.