Many out there have experienced the same as I; having lost access to admin functions in WordPress. Here’s my case:
working login-account for the admin-interface
just not being able to manage user accounts or manually upgrade to newer versions
Many solutions revolve around configuring your account to have admin rights again or to add a whole new account altogether. The account is supposed to have the administrator role again.
But what if just this administrator role has been compromised?
If you’re able to, download the plugin ‘Capabilities Manager Enhanced’ and install it via your FTP client. Next activate it in the admin functions of WordPress.
Now, somewhere in the menu bar, a new entry should appear, titled ‘Capabilities’. When you check out the configuration of the Administrator role, you will find many checkboxes cleared. Simply select them all and apply the changes.
Instant profit. This litteraly took me years to figure out.