Support Forum

I've been running this forum flawlessly for a couple of months, but a big issue just now.
It's integrated with MemberPress.
An existing member signed up in a different role (on purpose). I received an email saying "Password Lost and Changed for user: eSolutions". After that (may or may not be connected) there is no access to the forum. I get a page:
 "Not Found
The requested URL /forum/ was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request"

I've tried to "Reset Permissions" but it make no difference.

Please help ASAP if you can. It's 01:45 here in Brisbane but I'll stay up all night to try to sort this out - I'm losing business!!

Many thanks in advance for your help,
Dr Bob Gough