The most likely cause is a blown fuse (fuse blows if you try to use washers when the pump is frozen). With the aid of your handbook, locate fuse box and screen washer fuse and replace it with a fuse of the same colour and amperage rating. To prevent a re-occurence, keep the concentration of screenwash additive high in your screenwash reservoir as this also serves as an antifreeze (50% water, 50% screenwash is safest).
Good luck!!
Carl
January 2010