Using the Recovery Partition:
Power off the computer and turn it on after 2 mins and follow the steps immediately as you power on the computer
1. Press [F9] key few times as soon as you power on the computer.
2. Press [Enter] to select Windows Setup [EMS Enabled]
Read the ASUS Preload Wizard screen and click Next.
3. Select a partition option and click Next. Partition options:
4. Recover Windows to first partition only.
This option deletes only the first partition and allows you to keep other
partitions, and to create a new system partition as drive "C" .
Recover Windows to entire HD.
This option deletes all partitions from your hard disk drive and creates
a new system partition as drive "C" .