Steps to re- install Windows 7 are as follows
Step 1 - Open Start menu, type in Recovery in the search box and then hit enter to launch Recovery window.
Step 2 - Click Advanced Recovery methods to open Windows 7’s advanced recovery methods.
Step 3 - In the Advanced Recovery window, you will see two options:
# Use a system image you created earlier to recover your computer: If you have created a system image, you can use it to replace everything on your computer, including Windows, programs, and all your files, with the information saved on the system image.
# Re-install Windows (requires Windows installation disc): This option will re-install Windows on your computer. Afterward, you can restore your files from a backup. Any programs you have installed will need to be re-installed using the original installation discs or files. Existing might remain in the Windows.old folder on your hard disk after the re-install completes.
Step 4 -Click Re-install Windows option to start the reinstallation procedure. You will be asked to backup your files in the next step. Click Backup now option to backup your files such as document, pictures and music to a USB, DVD or external hard disk.
Click Skip and then click Restart button to restart your PC to start the reinstall process.
Note: When you use this method (Re-install Windows), the existing Windows installation will be moved to the Windows.old directory. You can retrieve data from that location after the restore completes. Any programs you have installed will need to be re-installed.
Step 5. Once you hit the restart button, wait for a few minutes to see the following screen. Select your keyboard input method and click Next.
Step 6 - In following screen, you will be prompted with reinstall Windows 7 confirmation box. Click Yes to proceed to the next step.
Step 7 -Now insert your Windows 7 installation disc and then click Yes to see the Windows 7 installing screen. From here onward you need to follow the simple onscreen procedure to complete the re-installation procedure (you can refer our Windows 7 installation procedure).
Step 8. Windows will take a few minutes to show the below screen, where you need to enter a username to your account.
Step 9 - Click Next to see the set password box. If you like to set a password for your account, type and then retype the password in respective boxes. Click Next to continue.
Step 10 - In this screen, click Use recommend settings and then select your time zone and again click next button to select your network type from available Home, Word or Public network.
Step 11 -You are almost done! You have successfully re-installed Windows 7. You might see the Restore my files box on the desktop. Click Restore my files button if you have done a backup in the step 5.
Step 12 -Finally, you might want to delete the Windows.old folder during the re-installation process by Windows to move your old installation files. Refer our how to safely delete Windows.old folder in Windows 7 guide to free up a few GBs of your hard disk space.
Step 13 - Install all your software and drivers.
Step 14 - Enjoy Windows 7!.