I have a Lenovo IdeaPad U410 running Ubuntu Desktop 13.04. I have an external monitor that I connect to via HDMI, and it's worked flawlessly for six months. I plug in my laptop, it detects the display. The "change display" key built into the laptop works for switching between the two screens. Never any problems.
This afternoon, when I reconnected my computer after taking it into another room for a bit, it didn't work. When I open up Display settings, it can't detect the display. I tried disconnecting/reconnecting everything multiple times. And most strangely, that same "change display" key now behaves like a Super key, opening the dash instead of toggling the display. Nothing at all changed between when I plugged it in this morning and when it stopped working a few hours later. I tried xrandr, that doesn't detect it either.
Anyone have any ideas?