Cannot log in: local account replaced with MS account and MS account inaccesable

There is.  You can go to this reset page to reset the password to the outlook.com account.

I'm still curious why your administrator account is missing in action, that's troubling that the fallback account isn't there.

First thanks for being so helpfull Shawn.

If I understand you right: when I created the outlook account I implicitly also changed the password of the 'User1' account and there is no way to access the 'User1' account with the original password (which I have safely guarded) anymore.

Assuming the above is correct I further understand that I can change the outlook-account password on www.outlook.com and thereby somehow the 'User1' password on the machine is also changed.

If the above is true then the "only" issue is that since the outlook-account was intended as a dummy account I did not bother to complete it properly (again: I could never in my wildest dreams have imagined that I would no longer be able to access the computer through the "regular" login process with User-Id User1 and the associated password).

Is there someone who can help me access an account where the account information has been only partly completed???

Thanx for your continued support.

The User1 account is still your one and only account (except for that admin account that we aren't seeing, which is strange).  The only thing that changed when linking to an online Microsoft Account is the "friendly name" sometimes called "display name".  In other words, it might have an email address there (or your full name, if your profile online has it), but the underlying account is still User1 on your PC.

And yes you can reset it -- it uses the same password used at www.outlook.com -- which means you should be able to go there to reset it.  That's one of the perks of using a connected account, especially if you have multiple computers, because everything, even passwords, stay in sync.

I don't think you're doing anything wrong, it sounds like the built-in administrator account has been disabled by some means, I could only speculate as to how.  Let's see if we can get it back.

Normally to force it to be active, you could type this at an elevated command prompt:

net user administrator /active:yes

However this requires that you are able to login to the computer first to open the command prompt and type that command.

So if you cannot do that, the next thing I would try if it were my PC is a Refresh or Reset operation.  Unfortunately these are both destructive in some way. Refresh is the safest because it doesn't remove any document/picture files from your account, but it's also unlikely to resolve the issue.  But the next step is more drastic, because Reset puts your PC back the way it came from the factory out of the box: literally everything is gone and it's reset like it was brand new.

I WAS using an account 'User1' which had admin rights (as described above this account seems to have disappeared and been instead only the dummy outlook account is available). I have not used an account "administrator" (I did not even know that it existed).

If such an account exists by default on the machine, then I do not understand how to access it per your instruction :

"1. At the login screen, click the Arrow Icon and select the Administrator account."

Please note that there is NO arrow icon pointing to the left on the upper left corner of the login picture to bring up all accounts existing on the machine (since there are no accounts to switch between I assumed).

The only "arrow"that I see one the login screen is the one with which you confirm the password (same effect as hitting 'Enter'). Actually the login screen looks exactly the same as when I boot normally.

I followed steps 1-4 described above and there it all happens exactly as what you have described.

Is there something mising? Am I doing something wrong?