Minecraft launcher won't start. What should I do?

I was playing Minecraft and suddenly the electricity went off. When it came back on, I opened my computer and clicked on Minecraft. The Minecraft logo showed up, then it disappeared (like it normally does) but the launcher hasn't appear. How can I fix this? (I have windows 7, if that helps with something.)

Added (1). hasn't appeared* sorry

Rebecca 08.05.2015

First try updating your java to latest version, if didn't work, or you already have it, then delete(+Restart computer before downloading) and redownload launcher, if didn't work try to completely reinstall your minecraft, delete minecraft folder and install then, make sure to backup your save files.

Jet 08.05.2015