Last night I found our bristlenose catfish, Andy out of her tank. I do not know how long she had been out. When I picked her up to put her back in her tank she was still breathing but she was dry and her tail was stiff. Once back in the tank she went belly up a few times and each time I turned her back over. This morning she is still alive but breathing rapidly. Andy is not moving much and even let me pet her in the water. Usually Andy is very skittish and hides at the sight of anyone or any noise. She is sucking the side of the tank out in the open and has not moved from that spot for a few hours now. I have also noticed that the bottom half of her body has turned lighter in color almost to the point of being completely white. Her normal color is black and goldishbrown. What can I do to help her?

She’s currently massively stressed thats why she’s changed colour and she’s not really moving. Pleco’s are one of the few fish that can actually survive out of water for a fair length of time able to take in atmospheric oxygen.

As long as she was alive when you put her in the tank and she’s not floating belly up any longer (she’ll have been floating belly up from taking in atmospheric oxygen).
Just leave her alone she’ll either recover or die unfortunately but since she’s not dead already within 24h chances are she’ll be fine just make take a few weeks to fully recover / settle back down. She’s in massive shock don’t poke or prod her any further just leave her on the glass.

Only thing you may want to do to help settle her down a little is turn your tank lights off and leave them off for a few days pleco’s are happier in darkness