Sometimes your Windows 7 installation becomes corrupt, and you need a way to recover, you can use the original Windows 7 installation cd. However, it is always good practice to make your own, specially if you are running a 64 bit version of Windows 7, and the installation cd will not work. Here are the steps to create a System Repair Disk.
1- First, click start–>Control Panel–>System and Security
2-Second, Click on Backup and Restore
3- Third, Click on Create a System Repair Disk on the left hand side.
4- Make sure you have a CD inserted, and click Create Disk