Was doing some searching and came across a post that described my issue accurately but not precisely... Rather than high jacking someone's thread. Thought I would post a new one.
Had windows 7 64bit along side Ubuntu on a dual boot configured laptop.
I wanted to wipe the hard drive completely and reinstall windows, then create a separate and bigger second partition for Ubuntu.
I was having trouble booting from my Windows 7 disk, it would keep booting into a menu that asked me which os I wanted to start..... I was never getting the option to boot from cd. I was repeatedly rebooting while holding f2, f12 and f10....to no avail.
I figured if I booted into windows i could run easus partition to erase the partition that housed Ubuntu. Once erased, upon reboot it still booted into the "os selector".
I then figured I had to create a new partition file system on the recently wiped Ubuntu partition. Upon completion the computer shut down.
Upon restart, I get: "error: unknown file system. Grub rescue>"
I am completely lost and need help.
I have the Windows 7 in the disk tray and want to install that first.
Can someone please help? I'm not extremely tech savvy, but do know my way around a keyboard.
I'm currently using my Nook tablet to communicate and it's beyond tedious.
I'm begging guys, save me!

I'm getting kind of scared guys. I know that sounds silly but this laptop is very important to me. I searched "grub rescue commands" in Google and all the things I found were not recognized.
I'm terrified to find out I ruined my laptop....

Tends to be hardware vendor specific. If you can't find a user guide, try <Esc>, <Del>, <Shift> ... I even had one Toshiba that you had to hold the <C> key down (for CD ... well, d'oh).
As a last resort I've been known to pull the hard drive out completely. That should pop up the BIOS menu.Nope - you have grub in the MBR, but you removed all the code that actually does the booting. The code inthe MBR basically just branches to that code and continues.

If you have another system you can pull the hard drive out and erase the grub code in the MBR, put the disk back, and boot that (with the CD) - it'll skip over the disk as it has no boot code. Easier to find the BIOS boot menu "magic key" though - watch the splash screen as you power-on the box.