You probably bent or broke the wiper linkage check under the hood and see if you can get to the wiper linkage from there to see if it just popped off. If not you will have to take the cowling off the bottom of the windshield and check it out.
A replacement linkage is not that expensive and if your halfway decent with tools you could replace it just remember if you remove the wipers do not leave the arms up incase they drop down and crack the windshield.