Just why are viruses harmful? Because they cause damage to your computer components just the way biological viruses are harmful to humans.
Some viruses can be harmless but annoying when they send silly messages or when they crash your computer system. But there are many viruses that can do great harm such as deleting the files that you need to run certain programs or to perform OS tasks. And some viruses pave the way for future attacks by opening up your computer and administrative functions.
Fighting viruses is simple: you need to install software that is called "antivirus" software. You'll need to keep this software up to date and always running on your computer. As well, never open up email attachments from sources you do not know.
Still, the odds are that one day your computer system will become virus infected. You'll lose critical data and programs. Files on your operating system will become zapped. So now what do you do?
The first thing to remember is not to panic. You might not even have a virus. Before you find a cure you need to find out if you have a virus and just what virus it is.
If your computer is still functioning, and you can access the Internet, you'll need to look for known and current viruses. Do a manual scan on your system and look for infected files and virus programs in your computer file system. Remember to search the computer memory as well since viruses can hide there.
Take the time to test several operating functions and programs. Something can go wrong with just one component. This method is not fool proof but the virus might just attacked certain functions and programs.
If your computer is not functioning you'll have to reboot with the use of an antivirus CD or disk. Did you prepare a boot disk? If you do not need to go back to step 0 – before the attack – and do the following: (1) create an antivirus CD and disk to boot your computer, (2) make copies of any software you have on your computer or organize the original versions, and (3) backup all your important files and data.
Scan your computer system once you've rebooted using the CD or disk. Search for the infected files or virus. If you find that you really have a virus infection then you're on to the next phase.
If you're using Windows there is a boot option that you can use called "Last Known Good Configuration". This option usually does not help but you may be lucky. Once you reboot your computer again you will not be able to use this option.
If you're using Windows you can check the dates of some of your main operating system files if they exist. The list is too long to mention here. Look at Microsoft's website for something called "Operating System Files". Or you can make a list on your own by using the WINNT directory and System32 subdirectory that can be found on a different computer. The dates need to match the other files so that you get the same service pack level.
You need to particularly check the lsass.exe and kernel32.exe. This is because hackers like to mess with them. You might find Microsoft updates but they are usually available in bunches. Anyone that has a different date should be under suspicion. No one ever said that this would be easy. To some degree Windows has some self protection functions and the ability to self-heal but this is nowhere near ideal. You need to replace damaged files with new ones.
If you're a Windows user you may have a Registry that has been corrupted. There are some tools that you can use to fix this. Do an Internet search on "Windows Registry repair utilities" for results. Then choose a utility for your Windows version. There will be no recommendation mentioned here since in six months it will out of date. Internet forums can be useful for finding opinions on updating versions.
If the virus has infected a program – such as software for word processing, the browser, or your email – you can uninstall the program and reinstall it. This can be annoying but is easy to do. Most programs will avoid deleting any data files that you have created by prompting you first.
The worst thing that can happen is that you lose data that you have not backed up. There are some Data Recovery services that you can hire to try to get this data back again. These services can cost a lot but your data might be worth the cost. You might be able to get some of your data back even if it looks gone forever.
Best of luck with viruses … since we've all had one at one time or another.