Reboot and select proper boot device or insert boot media in selected boot device and press a key? please help me proceed from this screen when starting pc.

Try putting in your windows disk and using the repair option, your hard drive could be bad or data corrupted, you may have to reinstall windows if you are unable to recover it using the repair console. run CHKDSK /p from the C:\ prompt in the repair console. If you still are unable to access the disk, try reseating the cables on the drive, or using a different power cable. If none of that works, replace the hard drive.