Help! 6Gb database shows as empty after backup & repair

OSX10.10.4; DTPOffice 2.8.6; Mac Mini 2.3GHz

I just loaded DT Pro Office, which loads my email database when it starts up.
During the startup process I got a message saying there were errors in the database, and did I want to load a backup, or repair & rebuild. So I opted for the latter.
Eventually DT finished the process, but my email database showed only an empty page with a Tags icon on it.
To the right of the database name in the left hand panel (Open Databases) there is an icon of a pencil with a line through it.
On my hard drive, I can see the database, which is 6.03Gb in size.
I tried closing the database and first reopening it, and then importing it from disc. No change.
I opened the restore backup dialogue, but the only available databases (from last month) show only a 1.8k and 3.5k option (or does that not refer to the size of the catalogue rather than the whole database?)
The only remaining tool is Rebuild, but that’s what I just did, so I’m loath to run it again without reassurance!
Is there anything I can do to get my database back?

No one here can help as well as opening a ticket with Support