Anticmos Virus

This memory resident boot virus infects the hard boot sector and stays in memory after booting a system from an infected floppy disk. Thereafter, it infects all unprotected floppy disks that are accessed in the infected system. It has a destructive payload of trashing the cmos RAM and Hard Drive C:\.

So since you didn't specify your OS - find a way to boot either from a clean diskette or cd-rom and replace the MBR and Boot Sector of your hard drive

Try using mcafee's stinger.exe it's a free download. It's also a stand alone product that can be run from a dos prompt in your a: drive
http://vil.nai.com/vil/stinger/

it must have effected u'r MBR and DBR u need to replac it, have u taken a backup of mbr.if not its tuff.ok try connecting it another pc as a slave but it is very risky.coz it may effect that pc also.if u r able to start u'r systm with a bootable floppy then format completely (just a try).next time use segate software and do take a back up so that anything happens next time to MBR and DBR u can always replace it. for now u have to send it to the manufacture for low level partition.or just not worth keeping it.
Tharun