Lost all photos after upgrading to the latest version of iCloud on PC

I was running an old version of iCloud on my PC. I had the photos backing up onto an internal HDD with mainly programs on the SSD 'C' drive. I upgraded to the latest version of iCloud to get the password add-in amongst other things. But it has broken my settings.

My photos are now supposedly backed up to my 'C' drive in a subfolder that does not physically exist C:\Users\[Username]\iCloudPhotos\Photos. There is no way to change this even if I open the program as an Administrator. The previous directory has not been updated since I "upgraded" to this broken version, so in effect my iCloud photo backup on this PC is now useless and unmanageable.

The only directory I can change is where Shared photos are put. But if I try to set that back to the previous folder on the HDD, it says "Invalid Folder" and that I am already syncing it with another application. It is under my OneDrive folder along with all my other pictures and has worked fine for years. But now it is broken by the so-called upgrade

[Re-Titled by Moderator]