There's a
guide on here, I've got a bookmark at home so if you've not found it by then I'll post it here. You can get into the electrical side, I think it's something to do with the bushes in the motor getting clogged that makes them stop working. But yes, so long as it hasn't expired completely you could probably get it going again, for a while at least.
I just had mine changed out as the car was in for a service anyway and the pump hadn't worked at all for a while so I figured if it wasn't totally goosed then it couldn't be far off.