Installed Programs "Missing"? - Windows 8.1

So yeah, I know a fare bit about hardware, but not so much on the software side...

I use Avast (free) and Malwarebytes and scan my system every couple of months just to be sure. Avast pretty much always finds nothing, but Malwarebytes usually finds a few threats. 

Anyways, same thing this time round - Malwarebytes found a couple issues. I selected "quarantine all". 

Another method I use is to go into "Installed Programs" in Windows and check the list to see if anything has been installed without my knowledge that I can remove manually. However, for some reason, now the list doesn't show the majority of my installed programs.

It shows Windows related programs (Microsoft related etc) and only a handful of other programs, but nothing else. Doesn't show Steam, Origin, Chrome, MSI afterburner, GPUZ, CPUZ, Core temp, etc... none of that. It's all "missing" from the list - yet they are installed and they do run just fine.

Some Google searching turned up some results indicating it could be an issue with the registry/keys - and I'm assuming that what malwarebytes found and "quarantined" somehow messed with my registry?

Is there a way to restore or have Windows scan for all installed programs to repopulate the installed programs list?

 

Appreciate any assistance.  

 

Thanks. :)