In Whiterun, I stole something and went to jail. I went down and then as I turned around, I got stuck between a wardrobe and tried sprinting out. Then I tried jumping. Neither of them worked.
Are you using a console or a PC? If the latter, just open your console and type in
coc whiterunorigin teleporting you to the Whiterun marketplace. If the former, or you don't want to use the console, loading a previous autosave/save is an option if available, although if you're asking here it probably isn't. Otherwise, just spam jump and sheathe/unsheathe and pray.