Use a hammer and some pliers and bang on it pathetically until the sprocket evens out enough to slip the chain back on.
Alternately, one could do the above near a bike rack in the Apartment Village during the Butler football game. (If the Apartment Village were any closer to the Butler Bowl, they’d be playing football in the kitchens.) One student had his family with him, and the father was cooking hot dogs on a portable grill (so cool–I’ll get a George Foreman or something like this one day). He immediately offered to help.
“Oh, thank you,” I said, “but if you just tell me what to do, I can do it.” I held up my hands: They were covered with grease stains.
“No, no,” he said. Whereupon he flipped the bike over, told his son to run into the apartment to get paper towels, and stretched his hand out for the hammer. Bless him.
When we were done straightening the sprocket and coaxing the chain back through all the various loops, I took it for an experimental lap around the Apartment Village. The Butler student, his mother, and his father were eating hot dogs and watching the Butler Bowl action from the grassy area near the bike rack when I returned. I gave a triumphant thumbs-up and thanked the family profusely.
“No problem,” the father said. “Would you like a hot dog?”
No, but thank you. Butler bulldogs. They never let you down.