First off, Welcome to DiscussCooking, Mary! It's so nice to have you on board!
As for your question, it depends on your recipe.
If it calls for FRESH parmesan, you will get the true flavor and consistency, which is kind of hard to duplicate with another cheese. Possibly romano would be the only thing I'd use as a substitute. Softer, more ordinary cheese, like cheddar, jack, mozzerella, etc, are not even a close match.
If it calls for POWDERED (like the stuff in the green can) you can use a mixture of romano and fine bread crumbs. Unfortunately, that stuff is also really salty, so you may need to increase your salt in the recipe.
What is your recipe? Maybe we can help you with the substitutions.