I made authority of the Administrator user demote in Vista

"Try this:

Click Start
Type lusrmgr.msc and press CTRL+SHIFT+ENTER
From there you should be able to manipulate users and groups, adding your normal user account to the local administrators group, or create a new user with local administrator rights.

If this fails to work, you could download Petter Nordahl-Hagen's Offline NT Password & Registry Editor as recommended on petri.co.il. Burn it to CD, boot to it and it will allow you to either promote a current user to a local administrator, reset the local administrator password and enable the account if all other suggestions fail. <-- this is free.

EDIT - hmm... I never realised that, the tool above also has the ability to 'Promote a user to administrator'. If you want to see a video/tutorial of it in action, check here."

"The built-in Administrator account cannot be deleted, but it's normally disabled on Vista.
Also, as far as I know, Vista doesn't let you delete the last Administrator account, so your description of the facts is quite puzzling. Let's first try a couple of long shots.

First long shot: Try to use Computer Management (right-click the Computer icon and choose Manage). See Users under Local users and groups. Try to see if you can create a new user or can add your user to the administrators group.

Second long shot: Under Administrative Tools (if not present in Start menu then it may also be in Control Panel), choose Local Security Policy. Select Local Policies and then Security Options and double-click ""Accounts: Administrator account status"" (which should have disabled as status). Try setting it to Enabled and OK.

If none of the above worked, you will need to enable the built-in Administrator account and reset its password (if any was specified). For example, ""Active Password Changer"", personal license $49.95, is advertised as a solution, so you may take a look at the downloadable demo. There might exist freeware that does the same which I don't know about. Your very last resort is reinstalling Windows."