You cannot recover the model from the "c2db" file. This is a secondary input file that is used to store mostly strings - like the element name, or the restraint tag, and so forth.

I can't tell from the image above if the _A file is there - this is your model input. If this file is not there, you can check the backup directory. You can select one of these from the "File Open" dialog. Below the graphic image you can see a drop box with the filename, date & time. The latest edition of the job is usually at the bottom.

You can also find these archives under \ProgramData\IntergraphCAS\CAESARII\Version\backup. Replace "Version" with your version number. Below \Backup you will find a directory for each job file. Within each of these you will find the most recent 25 copies of the job.

I hope this helps.