Site Administrator not able to amend journal settings - Access Denied

Hi,
my multi-journal site has been working well but a while ago, there was an erroneous edits on a single journal and now even the Site Administrator cannot change/amend it. I have tried the steps here but it is not working. It seems Administrator access to this single journal was compromised. Is there a way i can Reinstate the rights to the affected journal?

Best Rgds