Upgraded W7 - W10 And W10 Is Falling Apart

I waited to upgrade till the last day of W7 support cause I figured most holes would be patched by know but seems W10 is still pretty wonky and looks horrendous IMO. Seems like everyday I'm having to fix new things that weren't broken the day before. I think most problems are being caused by faulty upgrade possibly, and maybe I should have done a clean install instead of upgrade. But I have a couple very expensive programs installed that I no longer have the CD's or keys for so I can't lose those.

Some of the problems are as follows:
1. Restore point failure: I tried to do a system restore and I got an error message stating that it didn't complete because I didn't have access to some files.
2. Task Manager errors: Error"MMC has detected an error in a snap-in and will unload it, Unload the snap-in and continue running". Task manager opened after but none of the tasks that were there in W7 are there and its completely empty. And I'm pretty sure its not running properly.
3. Most of my desktop icons disappeared: Started pc up a few days ago and most of my desktop icons were gone. They disappeared on all my accounts admin/users.
4. Scanned system with MSERT and it found "Virtool:win32/defender tampering Restore" which was removed automatically.
5. When I run a Virus Scan or Malware scan the internet slows down to snail pace and is practically unusable. I have a decent rig that I built for gaming so its definitely not running out of resources. Its running on less than 1/4 available ram and is running at about 10-20% cpu while running scans. The internet never slowed downs in W7 no matter if i was running at close to 100% CPU or close to 100% ram.
6. Today I couldn't open any photos, music files, or video files. I was getting an error that read " Invalid Value for Registry". I figured it out. I had to go through all Microsoft Apps that come pre installed on W10 and reset them 1 by 1. Microsoft - photos, groove player, movies etc...
7. (This goes with #6) I had already changed photo, video, music files to open with "windows image viewer" and "windows media player" and today the settings had reverted to previous settings on there own which is why I couldn't open them.
Thanks in advance.

 

Forgot to mention that I keep getting W10 alerts stating that my antivirus is off and that I need to start it up. I checked in windows security and it says that my antivirus is "Snoozed" and that I have to fix the problem. I am running Avira AV and it looks to be running properly so not sure why I'm getting these alerts?

 

Ok will do thanks for the quick response.