I concur with Noel. But if you are NOT running an anti malware program, get one and check your system. Malwarebytes Pro or (and) Super AntiSpyware will find any bugs.
In addition to Matt's excellent advise if you don't have an anti-virus or if everything else you have tried and they all failed then you may have a virus. In either case I would add the following to Matt's advice:
1- run the free cCleaner:
https://www.ccleaner.com/ccleanerThis will clean out all of the junk that is not needed any more. Be sure to just run the cleaner section, that comes up first, and not the registry cleaner section.
2- run the free Rootkill:
https://www.bleepingcomputer.com/download/rkill/This will delete any root viruses.
3- run the free ADW cleaner:
https://www.malwarebytes.com/adwcleaner/For some strange reason this will find things that their anti-malware program doesn't find.
4- run an anti-virus. Note that the free MS anti-virus Defender/Security is a good one and it comes with Windows.
5- run an anti-spyware program. I use Malwarebytes Pro. They have a free version also.
Then keep your anti-virus and anti-spyware running at all times. These are always running on my Internet computer and only turned off when my music computer is off-line and I am recording and/or working on a song.
If you already knew this then sorry for the redundancy.