After installing Ubuntu 12.10, to my PC and giving a path in the external HD, its root directory only went into that and all of the files on the HD of my PC.
Now I require the external HD every time to go to either Win or Linux. I deleted the partition made by Linux from the disk management of Windows, and now I want to change the boot sector of my HD of the PC back to Windows.
The PC is not starting up and showing a Grub failure. I have the original Win 7 OS. I tried with that going to the command line, but what is the command that takes me to DVD? I've tried 'cd dvd' and 'cd/ dvd'.