Back and recent apps buttons quit working

My phone forced a software update day before yesterday and now my back and recent apps "buttons" don't work most of the time. I have no idea if the two are related, but I've tried powering down and rebooting, restarting, I've looked through settings to see if something got changed inadvertently. Nothing has helped. This is extremely frustrating because I cannot cycle through or close open apps and my battery life already sucks. I would appreciate any help that can be given.