Wipers don't work?

During a rain storm the wipers stopped working but I could still hear the wiper motor running. There may have been a pop sound before they stopped working.
How do I fix this?

'93" Dakota
V6

Same thing happened to me a couple of months ago. Turned out that the wiper arm that connects to the back of the wiper moter came unhooked. There is a plastic bushing that had cracked and the arm fell out.