how to remove worn virus

Solution
If it's actually a virus, nuke (reformat and reinstall) the computer.

Most likely getochkn is right though and you just have a dirty keyboard. If it's a cheap one, you can usually fix that by taking out the plastic sheet that actually makes the keys work, and wiping both that sheet and the bottom of each key with some rubbing alcohol on a clean towel (better yet if it's a micro fiber towel)
If it's actually a virus, nuke (reformat and reinstall) the computer.

Most likely getochkn is right though and you just have a dirty keyboard. If it's a cheap one, you can usually fix that by taking out the plastic sheet that actually makes the keys work, and wiping both that sheet and the bottom of each key with some rubbing alcohol on a clean towel (better yet if it's a micro fiber towel)
 
Solution