Repair My Computer Option is missing in F8 menu in Windows 7

Recently i reinstalled windows 7 from the dell factory image by getting into the F8 option at the startup showing repair my computer, but after the reinstallation , the Repair My Computer option is missing from the F8 menu, my recovery partition is available, but the option  is not shown, how can i restore the option or how can i reset the dell proprietary master boot record , to re enable the repair my computer option.