When I installed windows 7 so Accidently I disconnected the MagSafe adapter and my macbook pro ran put of battery and now when I turn on my computer so it will just a black screen
Welcome to the Apple Support Communities
It looks like your computer is starting into Windows and Windows can't be started. To start into OS X, press X key while your Mac is starting, and then, open System Preferences > Startup Disk, and choose Macintosh HD to always start into OS X
You are welcome
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