Well the error itself is a connection issue with the mysql server.
The software lost connection to the mysql server.
You have a host site where your pages/scripts are and the host provides access from your site to a mysql server.
Meaning call your host to fix.
It could be a one time issue,Due to the host was making changes. Now if you have a dedicated or vps server it may be your job to fix it.
But if you have a shared hosting account then you probably don't have access to fix any of it anyway.
If you enabled the server logs in the ubb control panel,it may give you more info on what happened.
I assume you have not upgraded UBB.
It could be your host changed the mysql server location.
The default is usually localhost.
Which can be changed in the ubb control panel.
So I would be surprised that you don't have multiple issues if you can't connect to the mysql server now.
So it could be a temporary thing with the hosting company.
