Power cut can cause data loss. The database part of an odb file sits in memory during edit process, and then is packed back into the file when the work is finished .
If your file opens in Writer and asks for coding selection, your file damaged. To restore it, you can try the following process.
Make a copy of your .odb file (to keep the original file) and change its extension to .zip.
If you can open the file with zipper program then there are some chances that you can retrieve your data.
If your file cannot open in zipper program, your data is probably lost.
When you open the file in the archive manager, you should see the following structure:
Go to the database folder, you should see these files:
Extract the script and data files.
Open the script file, look for any discrepancies, and try to repair them.
Create new empty odb file, open it with an archive manager and overwrite the script and data files with the ones of the old file.
Close that new file and rename it back to .odb, you should now be able to work with it.