Hello Niloo and welcome to Seven Forums.
It sounds like that last DVD might be bad. Do you still have a hidden recovery partition on your Asus? You can try this:
Start your computer. IMMEDIATELY start clicking the the F9 key and keep clicking. This should access the hidden recovery partition (providing your hard drive wasn't formatted and everything erased.) If the recovery option appears you might see these options:
1. The first partition is deleted (the others remain intact) and a new system partition C: will be created.
2. This option removes all the partitions from the hard drive and creates a new system partition C:.
3. This option removes all the partitions from the hard drive and creates two new partitions C: (60% of the drive’s storage capacity) and D: (40%).
You want to select # 1 and follow the instructions. If you don't have a hidden recovery partition you could do a clean install
. (Everything on your hard drive would be erased.) Or you could contact Asus to buy a new set of recovery disks.