I now have no Admin a/c

Hi, please try
Windows 10 no admin account
Enable or Disable Elevated Administrator account in Windows 10

clemenzina said:

Yes, the Yes button is missing.

So the tutorial you've been given a link to is the correct procedure for your situation.
Fix UAC prompt has greyed out or missing Yes button - TenForumsTutorials
- I've tried to write it so you can do each step without being overwhelmed by being told to do too much at once.
- If you have any further queries then post them here and I'll respond.

clemenzina said:

Apparently, in order to boot into Safe Mode in Windows10, I have to enable the F8 key, and that involves Command Prompt (Admin), and a Yes to UAC. That's a Dell video from 2016, is it still valid?

There is no reference to the F8 key in the relevant Tutorial because it is not used.
- In other circumstances, you might well use the F8 key but not for these circumstances.

clemenzina said:

Quote Tutorial: "3.1.1 If you boot up to a logon screen, it eases getting into Safe mode..." How? Is there a drop-down menu there that I've never had the sense to explore?

No, you have missed nothing. That paragraph introduces [3.1.2] a set of variations intended to guide you in slightly different ways depending on whether or not you have applied the utility netplwiz.

clemenzina said:

Would reinstalling Windows10 via Recovery* solve my problem as a last resort? Just asking, it's not something I want to do as it takes so long to get back to full "capacity" and this laptop is 24/7 engaged in doing stuff.

The procedure in the Tutorial will have you back up and running within twenty minutes and that's including reading time.
Do not even consider any last resort. You don't need to. Your problem is fairly common and has an established remedy [the Tutorial].

clemenzina said:

Whatever, it's going to be a while before I can embark on this, am a quivering wreck.

Do it when you have the time to spare. I'll get a notification when you post here again and will try to resolve any problems you have.
- Do bear in mind that some sort of user account corruption has lead to this situation so you would benefit from sorting things out fairly swiftly.

clemenzina said:

*I've already been advised to do a System Image but hadn't got around to it - where the heck to put it/keep it so it won't get lost?

Whilst I have not tried all system imaging applications, I know of none that will run until you have fix your current problem of the Yes button being greyed out.
- You could usefully back up your own files while you are waiting to fix the problem.
- We can all take turns to nag you about system images once the current problem has been fixed.

Denis

If I make my day-to-day a/c Standard, will I have to log off and back in with an admin a/c to do anything that invokes UAC? That would be awful.

Create your additional Admin account[s] first, write down password[s] and test it/them - only when you are sure that the new account[s] work should you consider relegating your existing account to a standard one.
- But don't forget that you have ended up in this position because your existing account has a fault so be aware that it might get worse.

It is worth having these additional, standby admin accounts ready for use so you know you can get into the system whatever has gone wrong with other accounts.
- I think most people think it is overkill to have two additional, standby admins and just make a single one.
- My reasoning is merely that I wanted to be certain I'd have one left even if one had gone wrong without my noticing. Not very persuasive at all.

No, you won't have to log off then back in. That's the whole point of UAC - whilst we all regard it as a security item, it was originally conceived as a convenience for admins.
Instead of

logging a standard user out,
logging an admin in,
doing whatever the job is,
logging the admin out then
logging the standard user back in

you just see the admin dialog and approve that [conceptually, the admin dialog is where the admin pushes the user out of the way, enters the admin password and then goes back to sleep].

A standard user justs sees a different form of the admin prompt

- an admin user account sees this, the "ConsentUI"

- a Standard user seees this, the "CredentialUI"

- a generic term for both "ConsentUI" and "CredentialUI" is "ElevationUI" but everybody says admin prompt / admin dialog / ... . If you use the proper terms you are liable to get somebody asking what on earth you are talking about.

My data is all on D-drive

So is mine. I do check that my backups are up to date before any non-standard job needs to be done. I have practised the procedure in the tutorial at least a dozen times and I have never had anything go wrong with my own files but I check the backups anyway.

there was no popup saying "Are you sure? You will have no admin a/c if you do this."

When Windows 7 first started, it stopped the user removing the last admin account. But then, presumably after an update, people started reporting the problem that you have experienced and in some cases their reports were detailed enough to show that Windows simply no longer stopped it and did not even provide a warning.

first thing I do with a new laptop is partition the drive

I also used to do that but I have since moved on to having two disks in each computer.
- My latest computer came with two disks
- My earlier ones had DVD drives which I whipped out and replaced with HDD caddies that fitted into the DVD connections. Looking from the outside, you would not know that anything was different.

I was trying to edit the tutorial for printing

I used to just print things like that as they stood and scribbled / crossed out bits as required.
Since I keep my older computers, I now just print tutorials to pdf and display them on the screen of another computer.

I am most likely to take the plunge in the wee small hours when civilised gurus are not available

I try to keep sensible hours so I won't be around in the wee small hours. But I will stay online till almost midnight and will check in to see if you have any more questions.

I would wish you the best of luck but you won't need any,
Denis