I purchased new hdd and installed ubuntu in it as I didn't had windows recovery disk available at that time. Now I have recovery disk for windows 7, so I installed it . And after finishing of installation a reboot was requested by system . After rebooting, instead of getting a selection menu for operating systems it directly started Ubuntu. Please help solving the error. I already have important data from Ubuntu on external drive so I wish to completely remove Ubuntu and switch to windows. I don't know Linux much. Please help!!