Hi, A few ideas, one is that the file is corrupted, but let's assume it's ok, then you could try to open the file in another program, such as; http://www.alexnolan.net/software/mdb_viewer_plus.htm
This would prove if the file is complete, or not.
Is that .mdb file the only one that won't open, or are there others?
Do you have a previous recent version of that .mdb file saved that could be loaded and updated?