Hello! I'm using a MacBook Pro (13-inch, Mid 2012) and running Yosemite on it. I had my MacBook unplugged and connected to an external monitor. The battery died and so the computer went off. When I turned it back on later, it wouldn't detect my external monitor anymore. I tried restarting with the cables unplugged and plugging them back in. I tried opening Color Sync utility and system preferences and neither see the monitor. I tried rolling my mouse over to the monitor, but it's not there. Just the main one on the laptop. I tried plugging the monitor into another macbook and that works fine. So it's something on the laptop which is wrong. If anyone has any possible solutions to this problem, I would greatly appreciate it. Thesis checkpoint deadlines are fast approaching. *sweats* Thank you!!