Fix You've been signed in with a temporary profile in Windows 10  

d80adc said:

Hi, yes I used the correct format C:\Users\Username.

I then deleted the registry entry with the .bak next to it which had the same SID as the Temp profile and rebooted. That's all I did.
I know I didn't do anything else.....

I'm afraid that action wasn't in the steps of the tutorial.

You would have wanted to delete the SID without .bak (if available) and rename the SID with .bak to remove .bak from the name, then correct the path for the ProfileImagePath value. It wouldn't have caused the profile folder to be deleted though.

You might check to see if there may be a "C:\Windows.old" folder that may contain a copy of their user profile folder in it from a previous installation to help minimize the data loss.

I hope they have a backup somewhere.

d80adc said:

So by deleting an entry such as this case it can cause the system to delete a users profile folder then?

No. The SID key and ProfileImagePath value in the registry only references what profile folder Windows will load for the user account, and does not affect the actual user profile folder. It will either be used or not, but cannot be deleted by simply editing this in the registry.

In your situation, and the few others above you, something else has caused the user profile folder to be deleted. Especially since you mention malware was at play.

d80adc said:

The folder was there and all their data was there but in the users profile. By the sounds of it the action of me deleting the profile path which contained the .bak has deleted the profile too.

I know it may mistakenly seem that way due to the coincidence, but it's just not possible. In all my years of extensive testing, editing the registry as outlined in the tutorial has never caused a profile folder to be deleted.

Since the Surface was infected, you might see if the folder may have been quarantined by the AV program.

That's fine. I welcome all results to be posted back to help others. I just wanted to be clear that it can't delete the folder.

Your mistake editing the registry wouldn't have deleted the profile folder either though, so no fault on you for that.

I'm just not sure what could have caused the folder to be deleted, but I can 100% rule out editing the registry.