It’s an educated guess that this is an embedded Base file and not a split DB. If so, there is probably little if anything that can be done through the forum to repair this. However, there may be a way to save your data/tables.
First way to access data is from Calc. Open a new Calc document. If the DB was NOT registered, you must first register it. From the menu
Tools->Options. In left column expand
LibreOffice Base. Select
Databases. In right pane, click
New and point to your .odb file (use browse) then
OK. You should be back to the Calc screen.
With a registered DB, use
Ctl & Shift & F4 (or
View->Datasources from menu) to view datasources. If you see your DB there, click the arrow on the left of the name to expand,and then you will see Tables/Queries. Expand Tables, double click the table name and the data should appear on the right. You can now extract data/tables into the spreadsheet.
If you can get at the tables in Calc, you can most likely recover the tables and data within.
First use a copy of the problem .odb file. Using an archive program (or change the extention to .zip) extract the files to a temporary directory. Next, create an empty split DB using the instructions found AT THIS POST. Copy from the extracted directory the files in the
database subfolder the “backup, data, properties, script” files to the blank split DB subfolder
database. You can delete any other files which were there already from the creation. Then rename each of these file to the name you gave the split DB - “backup” becomes “NEWDBNAME.backup”, “data” becomes NEWDBNAME.data", “properties” becomes NEWDBNAME.properties" and “script” becomes NEWDBNAME.script".
After renaming, open the split DB. If all went well, the tables should be available.
Finally, always backup your information - preferrably to a removable device and now on the same device it already resides on. Critical or necessary DB’s should be in a split DB not embedded. There are some known potential problems during opening/closing embedded DB’s.