I am running the new W10 OS. If I go to File Explorer I cannot access "Run as Administrator" the yes box is greyed out & states to type an Administrator Password & then click Yes ( the Yes box is greyed out so cannot use ). On the User Accounts page, there is my name & photo, under is my email address & Guest Account, Password protected ( can't access it either & can't ever remember setting up a 'Guest Account ' ) ?

There are a number of other Apps that cannot be accessed, same deal Yes box is greyed out so cannot "Run as Administrator" ?
Looks like I might have to format 'C' drive & do a complete reinstall ! I have tried a number of other suggestions as per google & forums without success. I really don't want to do a complete reinstall due to the time factor & file saving etc, but if I could complete a SFC & or Restore maybe this would highlight the problems so a fix can be undertaken !

The original OS on my HP desktop was W7 Home premium & W10 free install was installed over it. I presume ( noting that I am no PC expert but just average ) that W7 be installed first & W10 over it when available or offered .

Maybe a member may have other suggestions so it would be much appreciated if you can advise me of same ?

Cheers & Thanks again, Dennis