Lost local administrator permissions on my Windows 10 computer

I’m using Windows 10. I have always been the Administrator, or I was. I went to Properties for a program because when I clicked on Run as Administrator I was told I’m not the Administrator. Under the Security tab I am last on the list. Two, Accounts Unknown, are first, then System, I forget the next, then me. All of my permissions are gone, Please Help.

I am the only person who uses my computer. I have a Dell computer with Windows 10 – 64-bit operating system, x64-based processor.I’ve been ousted from my administrator position.

I’ve unplugged my comuter for minutes and hours, left my computer at home and took it with me, Recovery untold times, Router factory reset untold times, two AI’s. I’m exhausted.

I’m asking for help getting my administrator status back.