First of all, if Vista has system files that are corrupted or otherwise altered to a state that is not what is supposed to be there (by whatever), the only really good and reliable way to fix it is format the drive and use a tool (will be something that runs from a CD) that will clean the drive by writing to every sector on it to overwrite any data on the drive. The tool has to be able to ignore and overwrite even marked areas.
BUT, since you had to ask this question, I will assume you are not technically savvy enough to find or use those tools, and tell you that the best way to do it for you is get a legitimate copy of Windows Vista (from your computer manufacturer specifically for your computer make and model), which will be on a DVD(s), and boot (restart) from it. Follow the directions and answer the questions. It may ask you at some point if you want to format and restore your operating system back to original factory install. You want to answer yes. NOTE: THIS WILL ERASE YOUR HARD DRIVE COMPLETELY, AND MAKE YOUR COMPUTER LIKE IT WAS WHEN YOU FIRST BOUGHT IT!!! No personal data will remain. However, there may also be an option that will allow you to repair. As a rule, this option has been unreliable. So just format and restore to factory original. That works reliably.
In the event that your computer manufacturer cannot sell you a legitamate copy of Windows for whatever reason, go to some place like Best Buy and buy one. Make certain it's not an upgrade. That will not work for you. You have to have a copy of XP on your computer for that to work. Get a full install version of Vista. Then boot (restart)your computer from the DVD and follow the directions. NOTE: Protect your new DVD(s) from scratches religiously. You may have to use them to restore your computer again some day.
Then, once you have your system restored, go to http://www.avira.com/en/products/avira_desktop_products.HTML , and get either the premium or security suite, your choice. (NOTE: I am not associated with any company producing any software product) This is what I use, and have used to fix other people's computers. I am one of many local neighborhood geeks. Be sure to uninstall any antivirus software that comes with your computer (usually Norton or Mcafee, both of which I have seen fail, a lot).
Make certain that you maintain your subscription to Avira so that you get all the updates to continue protecting Windows. Maintain all Windows updates as well from Microsoft.com. Take the time to get to know how to use Avira. And do not get the free version. It is not comprehensive enough by itself, and must be used with other software protection to have complete enough protection. So, you being a non-geek, stick to the complete package. The free version does work very well, but it only does a few things.
When you begin this project, make sure you have all day to do it. Windows takes quite awhile to install, so have some other project that is secondary that you can fiddle around on while the computer is doing it's thing. Then come back to it when it requires your attention.
I sincerely hope this help. Have a great day.
Because, otherwise, computers could do nothing.
most viruses do nothing at all, the majority are obsolete or incorrectly made and they simply do nothing. But a Virus can do anything it wants to, including allow someone to see everything you type, search all your computer files, crash your computer, make certain programs not work, or greatly slow down your computer OR even use your computer to infect other computers.
nothing and everything
nothing everything is just fine its fun and people are very nice
Just Boredom all day basically! You get paid for doing next to nothing
The absence of nothing is everything. The absence of nothing is everything.
The computer knows nothing. It can only do what you, or someone else, tell it to do. The only information it can provide is what has been put in by other people. Who cares!!!!!!!!!!!!
the importance is nothing! XD
the importance of these mountains is nothing ;DDD
nothing
nothing
nothing