I really don't know what you did but it sounds like something in your
Access environment. If you can't figure a way out of it you might
have to protect all of your valuable Access applications and then try
to Repair your Office installation. If that doesn't do it, you may
need to Uninstall Office and reinstall it.
If all that might take to long in the face of urgencies, if someone
else has an Access development environment going, see if you can move
a copy of your stuff over there for emergency maintenance.
FWIIW it shouldn't be necessary to resort to drastic measures to
protect your application's design. As a last step before making it
available to the world at large, make an MDE. It is the MDE that the
troops should be running. You keep your MDB where only you and your
eventual relief can get at it.
By the way, if you haven't already done so, you should have split your
application into a Back End, with just the tables, and a FrontEnd with
everything else. Maintenance is much easier that way than trying to
maintain a monolithic chunk of data and design.
HTH