Hi DC7 ... and welcome to the forums ...
Sorry for the delay in replying ... any luck yet finding solutions?
Not certain why the restore point isn't available any longer - though I imagine it might be possible that some of the "PUPS" were located in restore points, and so were moved to quarantine. I suppose this might make a restore point unavailable.
As always, whenever faced with system instability, you will likely want to first save your most important data to external backups - before going on to the next steps in your repairs.
After making sure your important data is saved safely elsewhere, you could try an in-place "repair upgrade" of Windows 10. The quickest (and easiest) method is to visit the Microsoft Windows 10 website (it's best to use the one in the region/country where your version of Windows 10 was purchased), and choose the "Upgrade Windows now" option-button. It will download and install the latest build of your version of Windows 10 ... in effect "upgrading" it (which usually repairs what wasn't working in the older installation). If your computer isn't in good enough shape to visit the Windows website, you could download a Windows 10 iso file and create an installation DVD or an installation USB drive - and use that to reinstall Windows 10.
The repair install/upgrade is just a suggestion. There are other repair options you could try - (such as creating a new user account, and seeing if things are OK when using that account) - or using the repair tools in the Windows Recovery Environment. The repair install/upgrade is simply a bit easier and more thorough than most of the other options.
If you suspect any persistence of malware, use a bootable antivirus "Rescue CD/DVD" from AVG, Avira, Kaspersky, Avast, Bitdefender, Eset, etc. ... to finish the clean up.
Hopefully you've solved your problem already, and I've just been getting in my typing practice!
The Windows 10 site in the USA --
Windows 10
An article with full details about in-place reinstall/upgrades --
Repair Install Windows 10 with an In-place Upgrade - Windows 10 Forums