i m getting an error while installing OS

Clarifications

#1 Go into the BIOS and ensure that the CD/DVD drive is the first entry in the boot sequence.

#2 Check that the System CD/DVD you are using is valid and bootable - check by using it in a different computer.

#3 Make sure the Floppy drive is empty (if you have one).

#4 Make sure you're not booting with a USB thumb drive attached.

At present, the error you are getting, suggests to me that either the optical drive is NOT the first entry in the boot sequence and the HDD has already been formatted so there's nothing to boot from.

Or that the CD/DVD that you are booting from is actually booting first, but the disc is invalid.

[i]Edited due to Spanish Inquisition-ness - I began with 2 things to check![/i] :^0

This could be a HDD failure. Make sure BIOS can see it, install it on a different PC using a USB IDE or SATA adapter. Test for read or write capabilities.

Get a new HDD and put it in your case and put the old one in a caddy/USB self powered case.
Install your Operating system and then attach the USB caddy to your computer and copy over your data to your new drive.

You can download your HDD Makers testing Utility from here

http://www.tacktech.com/display.cfm?ttid=287

If the drive fails the test remove it and test in a different computer. If it still fails the Drive is Faulty and needs replacing.

But if ti passes the second test your Data Cable, M'Board or Power Supply in the first computer is damaged and needs replacing.

Col