It's always a nightmare when something like this happens! Probably the first thing you did, but have you looked at the impeller to make sure it's not blocked by anything? Other than that I don't really know what to suggest other than maybe do a water change if you're overly worried. As long as the bacteria has a source of oxygen then hopefully the colony will survive until the morning when you can go and get a back up filter.
Don't really know what else to suggest really, good luck and let us know what happens?