my computer has attacked virus so it is very slow.what we do?

Some people don't have drives D,E,F, just plain old C. If its not a dangerous worm that is taking over, usually its as easy as uninstall your old antivirus and get the latest version of it from internet, or a better antivirus software. There are many free antivir options out there, but in case of bad virus attack, those 15-30 days trial versions are good option as well. You can remove and replace trial software with free ones, after they do their job, cuz it should only take at most few hours, for an entire system scan and cleaning. I won't reply on the main, cuz the thread is 2 years old, but i thought this info might help you shivamkapila, to waste less time when disasters strike. Also a backup image for the healthy system, can cut on time waste to reinstall everything from scratch. It only takes 3 to 10 minutes to restore c: drive from image, but you must make sure you only have your operating system on drive c, before you restore the image, as well as when you make the image. Else data loss occurs if you rewrite c:, and drive image may get too big if you put other stuff in c whenever you plan to make partition backup.