Step 1

You have to first of all click on the Start Button. In the "Search programs and files" text box type "regedit" and after that click on the ENTER key. Click on the "Yes" plus after that on the "User Account Controls" window. This will unlock the registry editor.

Step2

Search out for the OOBE Folder. And after that Click on the arrows which are just next to the registry key to open up the registry folder:

HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/

Step3

And in the OOBE Folder, just click two times on the "MediaBootInstall" key.

Step4

And after that alter the Vale from "1" to "0".

Step5

And again click on the Start Menu. In the "Search programs and files" text box type as "cmd" and after that again Right-click on the short cut that emerge on the top. And choose the "Run as administrator" option. Click "Yes" on the "User Account Controls" window. This will open up the command prompt.

Step6

In the command line window, type: slmgr /rearm

and finally hit the ENTER key.

Step7

Shut the command line window as well as restart your Windows 7 system. After Windows 7 starts, click on Start Menu, right click on the "My Computer" as well as choose the "Properties" option. Type in your product key as well as activate the Windows 7 operating system.