"I am not just any virus. I am the Lord commander of viruses"
Malware is a program or file which runs on your device with the intended purpose to harm or even corrupt your machine.
It typically consists of using computer viruses, worms, Trojan horses, adware and spyware to perform attacks such as encrypting files, deleting personal data, altering or hijacking core computing functions and monitoring users' computer activities without their permission.
Typically, Malware is a collection of viruses that run specific code on your system which then proceeds to infect the machine with whatever measures it seeks.
What to do if you're infected?
If you detect something is wrong with your machine such as files being deleted, unknown pop-ups and unresponsivness then the best way to get rid of Malware would be to use Anti-malware software. Depending on the extent of the damage, it may be best to do a complete reinstall of your Operating System.