Introduction to Computer Viruses

A computer virus is a set of computer instructions or program codes that a compiler inserts into a computer program to destroy computer functions or data. It may invade your PC if you do the following things:

  • Continue visiting certain websites where viruses, spyware, or abnormal operations have been detected. 
  • Download files, apps, and plugins from unknown sites or receive the files from unknown sources.  
  • Use the pirated programs, unauthorized software and unlicensed games.
  • Use a new removable device on your computer without checking security or killing the virus with security software.

Usually, when a virus invades your PC, it will have varying degrees of impact on the system and applications. The weak virus will reduce the efficiency of the computer and occupy system resources, while the severe virus may cause data loss and system crash.

Virus Attack

How to judge whether your PC is infected with virus? Here are some symptoms making you able to realize that a virus infects your computer:

  • Programs will not work normally.
  • The computer crashes for no apparent reason.
  • The computer often restarts suddenly or becomes unable to start.
  • Bad disk clusters are inexplicably increased.
  • Disk space becomes smaller unreasonably.
  • System startup slows down.
  • Data and programs are lost.
  • Abnormal sounds, music, or some meaningless screen greetings appear.

How to Recover Files Deleted By Virus Attack

If your PC encounters virus attack, you should first of all check your PC to see whether your files are still there. If there are important files lost, what you should do first is to find them back before performing an antivirus scan, because killing virus first may cause your data unrecoverable.

Check If Your Files Are Hidden Or Deleted

Before you recover data, you should determine whether your data is hidden or deleted by virus. If the files are hidden by virus, the files are still there and you can find them back easily. 

Here is the tutorial on how to unhide your files via CMD:

  • Click Start menu, type in “cmd” in the search bar, and hit Enter.
  • From a list of programs, choose “cmd.exe“.
  • In the command prompt window, type “chkdsk F: /f“, and hit Enter key (Replace F with the drive letter of the partition where files are lost).
  • After the above process is completed, type “F:“, hit Enter, type “attrib -h -r -s /s /d *.*“, and hit Enter again.

Then you can go on with the next movement – running the antivirus software to kill the virus.

However, if your files are not found and is proved to get deleted by the virus, you must use data recovery software to rescue your data and this is usually not free.

Recover Lost Files With Data Recovery Program

Usually, data recovery tools are third-party tools and are not free. If you want to find the best or reliable data recovery software, the post – Best Data Recovery Software for Windows/Mac/Android/iPhone (2020) – may help you.

However, before you use software recover data, you should know that it’s possible that the data recovery software may fail to rescue your data or the data it recovers is corrupted. The reasons for this situation may be various but you should be prepared for that. if you are unfortunately in this case, I recommend you to apply for refund.

Tip: Some people may advise you to use system restore to recover data. This is not available, because system restore points only back up computer’s system files and application files. They do not contain personal files. 

Kill Virus

After finding hidden data back or recovering files deleted by virus attack, you can then run antivirus software to kill the virus. You can use a third-party antivirus program or the built-in antivirus software—Windows Defender. 

Windows Defender is an antivirus program developed by Microsoft. It is also a reliable and powerful antivirus program. If you don’t install any third-party antivirus, you can run it, here is the brief guide:

  • Click Start button and select Settings
  • Select Security & Update.
  • Choose Windows Defender and then click Open Windows Defender Security Center.

Click Virus & threat protection and then click Quick scan.


Nick is a Software Engineer. He has interest in gadgets and technical stuffs. If you are facing any problem with your Windows, feel free to ask him.


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