AVG PC TuneUP: Undo Changes fails

Hi Reiny,
I noticed that you contacted support after creating this question. What is current status, were you able to solve it or do you still need our assistance?
Thanks

I Installed Free (Trial) Version of AVG PC TuneUp. It has since expired.

Prior thereto, I allowed it to "tune-up" my system etc. and I accepted the changes.
I later shutdown and the next day restarted.

My main user account is (was?) also the Administrator account but I could not access "My Computer" or Windows Explorer or my documents, or directories, files etc.  I would receive the following msg when I tried to access my files or access Control Panel:

 "Windows cannot access the specified device, path, or file. You might not have the appropriate permissions to access the item."

I then decided to "Undo  Change"s made  by AVG PC TuneUp using  AVG Rescue Center yesterday to  restore the changes carried out and listed . 

I rebooted and everything seemed back to normal. I continued my daily work, creating several files and spreadsheets etc., working for several hours, saving my work during and also before closing any applications. 
I later shutdown.
This morning I started my laptop and logged into my main user account.  It is again denying me permission to access my files:I receive the same message in the dialog box which appears when I try to open directories or even Control Panel.:
"Windows cannot access the specified device, path, or file. You might not have the appropriate permissions to access the item."
 
I opened AVG Rescue Center again, but cannot undo changes as no changes are shown to have taken place.

Within AVG Rescue , under "Tasks, System Recovery", I have 4 Backups listed.
I have not restored to a backup point as I don't wish to loose any of my work completed between the backup point and today.
Why did the "undo changes" not hold?
How can this be resolved so that I can again access my files?
Can you help me please?
Hi Reiny,
I noticed that you contacted support after creating this question. What is current status, were you able to solve it or do you still need our assistance?
Thanks