Master Design missing..

About a year ago a made a replica of a database.
Then, after some stupid playing around / mistakes from my side the master
is 
lost / gone.
My company still uses the database, but only a replica, which means I no 
longer am able to add / modify tables etc.
I really need to make some modifications (add fields etc).

So, anybody out there who knows about way to make a new Master from a
replica?

The database is made in Access 2003.

Thanks!