Can't get Win 7 Update to check for updates

Dell Optiplex 755, Win 7 Home. I have inherited this PC from the estate of a deceased uncle. I was with him when he purchased the PC so know it came from a legit source. Moreover, I have seen him successfully use it. The last recorded Windows updates are from July, 2015, when the PC ceased being used and a Win 7 sticker is still affixed to the case and the number is readable.

When I bring up the Windows Update site, I don't get an error code but do get a message telling me that 'system administrator' permission is required. So far as I know, there has only ever been one 'Administrator' user account account ever set up (and it still exists) and no password was involved, so far as I know.

As this may be a 'user' issue, how do I get to the 'super administrator' account and how do I get rid of any password that may have been established? Alternatively, would it be helpful to do a system reset to the date of the last update?

Otherwise, suggestions, advice, pointers to an appropriate tutorial, or anything else would be most appreciated as I would like to get this PC operating properly again

Windows Update errors "0x80070002" or "0x80070003". This problem occurs when some files in the Windows Update are missing, even though the update is downloaded and extracted successfully.
Run System Update Readiness Tool & post CheckSUR.log.
It may take a while to complete, be patient.
The log will be temporarily located at: C:\Windows\Logs\CBS

First, a clarification. The PC in question is a 32 bit Dell Optiplex 755 running Windows 7 Home Premium. The last successful Windows updates were in July 2015. My apologies for not being more precise originally.

Per your advice, I downloaded what I thought was the System Update Readiness Tool. The downloaded file was <Windows6.1-KB947821-V34-X86> and named "Windows Update Standalone Installer". Assuming that this is the correct file, it would help if Microsoft consistently used the same name for things. Upon clicking on this file, it returned a message "Preparing for installation" followed by "Searching for updates on this computer". After a while, the message "Do you want to install hotfix for Windows (KB947821)". When I tried to install the file, the message "Some updates were not installed" appeared. I have tried to install this file both with the Internet connection active and disconnected and both with Kaspersky Internet Security loaded and not loaded. All attempts to install the file failed.

I also tried to run the Brink option 3 .bat "Windows Update - Reset" file. This failed as well.

Otherwise, the PC appears to access the Internet without difficulty. I am more baffled than ever.

did u check to see if SURT created a log? C/windows/logs/cbs

Yes, there are several things in that sub-folder. Which item do you want to see?

CheckSUR.log