How can I free my computer from virus???

There are several ways to get rid of viruses. One of the simple way is to get a good anti virus software and update the software. Then do a full scan of your system. For this i recommend solo antivirus. It is small but powerful anti virus. There are several in market. Another way is to format your hard disk and reinstall all your progerams once again.

If you are using Windows operating system, there is a feature called "System Restore" (Start Programs Accessories System Tools System Restore). Using this, you can restore your computer to a condition it were before. You calculate a rough idea about the date your computer was infected by the virus and then restore the computer to any save points earlier than the date of viral infection. This way, all the damage done by the virus will be reverted. Now use a good anti virus to detect the virus in your system, and heal it. This way, you can recover.

i my computer i am using this kaspersky antivirus and USB drive security things for protect my computer from virus and my friends all using the same we didnt attacked from virus mainly use USB drive security it will protect virus while autoplay of USB pen drive its safe

If you have files that had been deleted because of viruses. I don't think you'll ever recover that unless you have a backup or a recovery system in your computer. Anyway, you must have a strong anti-virus program installed to get rid of the viruses, try to purchase a good anti-virus, Kaspersky or Norton for example, I think they're reliable. Also, it's also important to have anti-spyware if it doesn't come along with your anti-virus program 'cause most anti-virus program that downloadable free like Avira and AVG doesn't have that feature, you must then install one like Spyware Terminator. It guards your computer from spyware, malware, adware and other dangerous stuff. You might wanna be careful to the sites you're visiting in, make sure that it's virus-free so you're computer is safe and if there's no other way to get rid of those viruses, I suggest, you reformat, that's the last resort.

First you have to run antivirus check and update on regular basis. if you pc is crash then try to recover your files with data recovery software.

Virus is the common problem to everyone i suggest you to have an antivirus and keep it updated. I think mcafee is capable of detecting all types of virus so install it and be protected from virus. Most virus come from internet and pen drives so format your pen drives at regular intervals and scan them before to start to work on them.