lost administrator user account

Can anyone please help. I added a new user yesterday along with the
original administrator user. When I came back to my computer, the
administrator was gone and I am locked out of my computer. The new
user only has limited access, so I cannot due a system restore or
anything. I have so many documents I will lose if I format the hard
drive again. I have called Dell and microsoft, and no one will help.
Please any suggestions would be great. Everything I try says access
denied because of the limited user.
Thanks,
Rhonda

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