There is a green box, a bit smaller than a pack of cigarettes, under the glove compartment on the right side. It is called electric window ECU, it has relays inside which are prone to sticking (I think). Anyway a good bang on this thing will solve your problem, temporarily.
Mine has been like this for years, occasionally stops working then works again. Relays can probably be replaced but I don't mind giving it a slap once a month or so.
if both stopped working at the same time, it should be the problem with the relay or maybe fuse?
I had a problem that drivers window was moving really slowly and then stopped entirely, but that was a problem with worn window guides. This doesn't seem like your problem though.