Administrator user changed to standard. HELP

Hi
I've got a Macbook Air running on Lion version 10.7.5.. Never had any problems in the 1,5 years I've got it, but today it changed me from administrator to standard user.. So can't do anything..

How do I fix this??

How do you know this change has taken place?

Do you have more than one user?

What issues/errors are you seeing?

I've only got one user.

ATM I can't download or install anything, change the firewall etc..

When I open the users and groups in settings I can see that I'm now only a standard user

I can't come up with a scenario where the user would just change.

However, please see the thread below for info on restoring the admin user:
http://www.mac-forums.com/forums/os...lion-admin-c-change-standard.html#post1278691