"Dumb girl" question

OK. I have this small room air conditioner - one of Wally World's finest - made where else? In China. So, I was taking it out of my window getting ready to move. It is quite a heavy little sucker and the ax murderer had put in place with a piece of styro-foam rather than using things like screws or nails. (He was always lazy as well as being an ax murderer). So I pull out the styrofoam and the whole air conditioner falls about 15 feet to the ground below. Ooops!

I get the thing 400 miles across the mountains to my new apartment and discover that in its suicide hurtle, the air conditioner pulled out one of the prongs from its plug - the "fat" prong is now missing.

Here's my question: Can I go down to the hardware store and just buy a new prong and stick it in there where the old one had been? Or do I have to pay an electrician to put in a whole new plug in which case I may as well go down to Wally World and buy a new AC. Advise please.