Santosh bro, i know the pain. I know the pain you get from computers. bhae pani nahuney, nabhae pani nahuney. I can't really tell the pain from wife hai, mero wife chai chaina, wife le wifi hatako le gali gareko rey! eheh, tara virus scanner chai auta cha free, called Avast. get it here - http://www.avast.com/ then update. But with all that corrupt or damaged files, I suggest you repair or reformat. If you just pop-in the XP cd, then it should give you the options. If you turn pop in the cd, turn off the pc, turn it back on, then it should allow you to boot from the CD if that cd is still good. But to run Boot from CD disk, you must change the boot order in BIOS. Restart your computer and if you see something like Press any key to boot from cd... you can go ahead and start with that, if you don't see that, then go to BIOS. Turn off your computer. while turning on, hit F10 or F2, sometimes its different in Different PCs. Enter BIOS mode. find BOOT ORDER from menus or submenus. Change CD-ROM to number 1 by moving it up to top. Then save changes and exit by hitting esc. restart. And let CD boot your PC. And go to Windows Repair.