When Windows becomes unbootable, you can use system recovery tool,

in Windows 7, the installation DVD options hlps recover the system.

Windows 7 also incorporates a very interesting feature: the creation of a repair disk directly from the system.

Here is How!..

In Control Panel, click System and Security (System and Security), and then click Backup and Restore (Backup and Restore).

In the left pane, click Create a system recovery disk (Create a system recovery disc);

Insert a blank CD in the DVD, and then click Create Disk (Create Disc).

..........................disc is created is a few seconds:

To check, its working.........Jus reboot the system on the DVD player.

After loading the files, select the language, and then click Next (Next).

(This will automatically find the Windows Installed DIR) Windows 7 installed the system is found, click Next (Next):

The recovery tools appear: These are the Windows recovery options

Repair boot (Startup Repair)

System Restore to an earlier date (System Restore)

Restoring a backup image (Image Recovery System)

Memory Diagnostic Tool Windows (Windows Memory Diagnostic)

Command Prompt (Command Prompt)