In order for a Windows operating system to "recognize" a file type, someone (usually an application developer) must add data to a database called the registry. This data tells Explorer (and other programs) what application handles file of that type. When you click on the file, it can launch that application. "Unrecognized" file extensions are simply extensions for which this has not been done; if you click on the file, the operating system doesn't know what to do and will tell you that. It doesn't mean the file is corrupt or unusable.

Just follow bquam's instructions and you'll be able to restore if you need to.

OrangeCD's databases have a .DAB extension. If you want to test restoration you can rename the file to another extension (be sure you remember which one it was to you can rename it back again). Then make a new database ('Database/New Database') and restore to it ('Database/Restore from backup...') and follow the prompts. If you're not sure where your database is located, choose 'Database/Manage database/Properties' and click on the 'Details' tab. The Folder Path is the directory, and the Name is the name of the database.