I agree with the overall premise that you should get a tax professional involved, even if you did not have any activity.
You will most likely receive correspondence from the IRS as a result of the late filed returns. The minimum penalty mentioned by @Anonymous_ has varied over the years so depending on the year your penalty will run from around $210 ish to the $435 for the respective year the return was filed late.
Your tax professional will be able to help you respond to the IRS notice and possibly get a tax penalty abatement. You will need to come up with a reasonable cause as has already been noted.
Keep in mind, your C corp was not "suspended" in the eyes of the IRS.
Also make sure you contact your state to see if there is something there that needs to be filed as well.
Best of luck in getting this resolved.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
