Since this started with a power outage, the first thing I would try is to delete the Photoshop preferences file but first save your workspace configuration so you can return PS to a setup state that you are familiar with more quickly. There are several ways to reset the preferences file and it depends somewhat on your system and version of PS but you can just google "resetting photoshop preferences file". In most cases starting PS while hitting Cmd-Opt-Shift immediately upon launch will do it but there are other ways too.
If that doesn't do it, it is possible that the power outage either dammaged the video card or damaged a video driver or some other piece of software.
