Error Shown
Unknown Filesystem Grub Rescue
How It May Happen
There are many reasons, but most commons one is- If you have installed Ubuntu along with windows, and you mess up with the partition or uninstall Ubuntu. In that case, the Grub is also uninstalled and since windows can’t find it, we can’t log in. Any system to boot into main memory, It requires MBR (master boot record). When MBR is damaged the system is no longer able to load in the operating system. And the error of grub rescue is shown
Follow the steps
Insert Windows 7 Installation or DVD win recovery disk, if you don’t have them, you can use Hiren’s boot cd.
Boot in cd/DVD drive. Usually, this is done by press combination of F8 or F12. But since this varies from system to system, I suggest you Google ‘How to boot into cd on ___’ followed by your laptop model no.
In Hiren boot menu, select boot from hard drive Windows 7
Press F8 immediately then Select Click Repair your computer.
Select a language to click next, Click the Command Prompt and enter the command bootrec /fixmbr
Reboot the computer and you are good to go. If you face any problem, let me know in the comments below. Next time, if you are afraid to create another partition for installation, I suggest you use the wubi installer. This lets you can install Linux on the same drive where you have to install your windows and is very simple to use. You can select the OS during the start-up process. Read More here.