I just reinstalled Windows 7 on my PC which erased my Master Boot Record and I can't boot into my Ubuntu 12.04 Precise Pangolin partition. The computer in question is an ultrabook, so I don't have a CD drive to boot from. Is there a way to repair the MBR from Windows?
If you have a usb thumb drive, you can use penndrivelinux from windows to make it bootable with an applicable distribution. From there you can fix it using boot-repair.
Please see: https://help.ubuntu.com/community/Boot-Repair