About 6 years ago I was told I have a paralyzed diaphragm. Is there anything that can be done to correct this?

Yes. A paralyzed diaphragm is usually treated if there are associated respiratory symptoms. This can be handled by surgical plication (shortening the diaphragm) or diaphramatic pacing. Normally, this is not necessary. Consult your doctor to see if these options are available.
Unlikely. Confirmation is by physical exam or fluoroscopy some re overly may occur, depending on the initiating cause. Post cardiac surgery some induced by stretch or cold seem to recover. After a cut nerve it is not likely to resolve but the body has some adaptive measures.