If nothing you do works, it could also be a hardware problem.
Most likely it's bad RAM or a failing power supply.
It was annoying, but the effects were easy to detect and contain.
Today, in addition to traditional viruses, there are Trojans, worms, ransomware, spyware, adware and plenty of other "wares." The computer industry term for all this is "malware." Even state-of-the-art computer security can't always keep up with new threats.
This is where deep-cleaning anti-malware software like Malware Bytes will shine.
If that fails, you'll need to use a rescue CD like I mentioned earlier.
If you see items you didn't send or post, change your account passwords immediately.
It could be snagging your passwords, sensitive files or other vital information.
For decades, it's been making computer users miserable. In the early days, a virus would delete your files and spread to other computers.
Unfortunately, it looks like computer viruses are just getting stronger and smarter.
Perhaps you notice a post on your Facebook profile you didn't write. If your friends and family click the link, they're infected and the virus spreads even further.
Keep an eye on your email "sent" folder and on your social network posts.