look at the wiper motor under the hood on the firewall. Check for any loose or freyed wires. If any water has leaked down causing a short that might be the problem. I know that they can get pretty price, like $80 or so, so it would be an expensive guess to just replace the whole thing. Try turing the wipers on periodicly while driving(raining or not) to see if they work. If its just a random thing it might have to do with the switch in the column. If not, my guess would be the motor.