If you would post a photo, perhaps someone could give a good guess as to make & model, to help in your part search.

To be honest, as a house brand gun with no serial #, it was made before 1968 = 39+ years ago, chances are that parts will not be available, leaving you with limited options.

On the flip side, "Gun does not fire" does not always equal "Broken firing pin", several things can be the cause of the malfunction.

First things first, disassemble, clean, inspect......See what you've got, then you,ll know what you need.