2001 rear window

Today was hot so I left all windows open about an inch and when I went to put them up the drivers side rear window went up but made a loud bang when it reached its end now I'm afraid to try opening it in fear of it going down and not going back up,any ideas?

Lots of issue with bad regulators on these cars, Napa/ Dorman make improved replacements, take it apart and see whats what.

Thank's for the come back but the regulator was ng,when we tried to run it again the window fell so I ordered a regulator on E Bay for under 50$ and should arive today,it may not be the best in quality but I might not ever use it again.