While updating an app, it froze and now won't open, close, stop updating, etc.

I started to update an app on my something's asked away to do something else. I noticed the next day that it was still updating. I couldn't open the app at that point, nor close it, nor force quit, nor cancel the update. I tried to reboot my iPad and it still didn't clear this trouble. I don't want to delete the app and reload because then I lose all my data and progress. Help! What can I do?