It appears I’ve managed to do a pretty stupid thing – personally I rather feel like Windows let me do a stupid thing, but that’s probably a matter of perspective 😉
Anyway, I was trying out some things with UAC, looking at the way different elevation prompts are displayed depending on whether or not the current user is an Administrators member or not, and so on. Previously I was working in what appears to be the default configuration, which my user account being a member of the local Administrators group and the Administrator account disabled and without password.
I activated the Administrator account and gave it a password. Then I removed my own account from the Administrators group and added Power Users instead. I played around with this setup and then decided to go back where I came from – only I made a mistake, I disabled the Administrator account first, before assigning the Administrators group back to my own account.
As a result, I can’t currently find a way to get Administrator privileges on my system! I can’t log in as Administrator because the account is disabled. For the same reason I can’t use the "runas" command to run any admin tools. And elevation offers only my own account (pretty weird that – why does it offer to elevate into my own account if I’m not an Administrators member at all?), which allows me, after entering my password, to bring up Computer Management – but I still can’t make changes to any account settings, obviously.
What do I do? I can see that I wasn’t thinking enough before making those changes, but I’m still having a hard time believing that I managed to lock myself out completely, i.e. the only solution is a restore from backup. Any ideas, please?
Update: I found a solution on this very helpful page: http://www.jimmah.com/vista/Administration/locked_out_of_admin.aspx I feel quite lucky that the no. 1 option actually worked for me and I didn’t have to use any of the other two – but at least there seems to be hope even if the situation is worse than mine turned out to be. In case you need that article and the above link should have stopped working, I have a local copy of it that I might be prepared to pass on in that event. Thanks to everybody who helped!