Need to Gain Admin Acess

I do not have Admin access. I thought I was given this access by the person who built my website (2yrs ago), which did not happen. I can in no way get hold of this person now. I do not know the username, password or email address that was set for the Admin user. I need to edit and update my website. I do have log in access which only allows “user level” access. I can not publish my changes/updates.

Please tell me how I can get in there to either change my user access level so I can make the changes and updates necessary. OR change the Admin log in email, password in username to my settings. I have also contacted my domain hosting company and they can not help me.

https://www.bridgingdemand.com
Version 3.7.11 – I am not able to update the version either.

Thanks.