On my 93 Toyota pickup where the door hinge bolts to the body of the truck has rusted a little and broke loose from the body on one side and my door is sagging. Any ideas on how to fix this?

 

You do not clearly say exactly what part rusted. You also say rusted a little, yet something came loose? That is not Little.
No other sensible solution than fix/replace the rusted part.

 

the body of the truck where the hinge actually bolts to the body is what has broke loose

 

Got pictures? Its hard to tell exactly what your talking about with out seeing it. How bad is the rest of the rust around the area?

 

If you're just trying to eliminate the door sag for now, and not repair the actual rust, I'm sure you could patch another piece of metal or plate over top and then mount the door hinge to that, but like the others have said: it's hard to know exactly what you're talking about without pictures.

 

A picture paints a thousand words.

 

Right behind the hinge

 

SEE? How could we have known that your door is made different from ours?

IF you cannot weld but have access to metal behind that area, remove rust, apply rust converter, paint to prevent further rust.
Make a reinforcing plate behind body sheet metal. Threaded plate or use nut behind it. Mount hinge.