Quick Question - Wiper Control Knob

My wife has a 2002 Intrepid (6 Cyl, 4 door if that makes a difference)

When she came home last night, the control knob for the windshield wipers had come off (It looks like it just popped off and does not look broke). I tried to just stick it back on there, but that didn't work. (It didn't go in all the way).

I realy don't know much about cars, but any ideas on how I can fix this without having to go to Autozone and order some expensive part just for the knob.

Thanks for any and all the help.........

hate to be the bearer of bad news, but if your washer switch part of the multifunction switch broke off, you're going to need to buy a whole new switch. There's no real fix for that. Hope this helps.