I am confused, so I am also going to use this question to get clarification and fix my computer.
Some background: I had Windows 7 on a 1 TB HDD and decided to partition my hard drive into two ~500 GB partitions, one for Windows 7 and one for Ubuntu or whatever flavour I desired (like a sandbox partition...)
I installed Ubuntu but the installation had issues so I decided to uninstall. Note before the uninstallation I had to press f12 when I turned on to boot from my primary HDD, then choose what OS I wanted to use. Undesirable, but it worked.
Anyway, after I decided to uninstall Ubuntu I went into Windows 7 > Start > Computer > Manage and deleted the EXT4 filesystem (Ubuntu partition) giving me 4xx GB of free space. However when I restarted Windows 7, I am now unable to boot Windows.
When I DON'T hit F12, I see a blank screen with a flashing underscore. When I DO hit F12, I choose my primary HDD, and then I get a GRUB error:
Unknown filesystem: grub rescue> _
Something I'm unclear of: GRUB boots linux partitions, right? What boots Windows? Is GRUB "overwriting" the Windows bootloader? How can I completely get Windows back to normal? (IE, It boots automatically without hitting F12.)
Thanks for any help, I'm on a live CD version of Ubuntu right now until I can get back on Windows.