To install Windows 7 boot from a bootable Windows 7 install disc and follow the prompts. You might like to remove all existing partitions as a first step.
If your computer came with a recovery disc, or you made one yourself, use that instead of a generic Windows 7 disc, so you don't need to go looking for the right drivers.
One day my computer's windows got stuck on the login screen and didn't login and opened to an temporary account so I installed Kali Linux by formating my C: drive (but still Windows 7 came but I was unable to log into it)and used it for some days and to remove my Kali Linux I used Kali Linux Live (from usb pen drive) and fdisk command to format the drive and then after I opened the computer error named "no such partition "came and Grub Rescue appeared then after watching some tutorials I removed Grub and Installed MBR using the same Kali Linux Live and now when my PC boots it says "this device is not bootable press any key" what should i do now.
Thank You

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic