Although you did not indicate the content of the contact, presumably this is an examination of the corporation (and not a collection
The general process for that type of case will be for you to respond the agent's request for information (either informally or in reply to an Information Document Request or IDR).
If there is an open year for which a return was not filed that return will need to be prepared and given to the agent. Whether or not the corporation had a net profit or loss that corporate return is required.
Since there may not have been any final return filed you may also be asked for evidence that the corporation ceased doing business, and when.
At this point, it may be advisable to find out just what the agent wants; but you can, and likely want to, begin the process of gathering (and as needed, reconstructing) the bank and financial records for the final year tax return of the corporation.
The bank records should include up to the last month in which there was any account still open and the final statement that shows zero balances.
In summary, you will need to prepare
any returns that were not filed while the corporation was still in existence and document, to the best of your ability, the end of the corporate existence including the disposition of the corporate assets.
Please remember that at any point in the process you can tell the agent that you would like to obtain a representative and that will stop the examination until you do. That is, if you are ever uncomfortable with the requests that is an option.
Although you should have had it in the material given to you upon initial contact, you can find Publication 1 outlining your rights at http://www.irs.gov/pub/irs-pdf/p1.pdf
See also http://www.irs.gov/uac/Taxpayer-Rights
Please ask if you need clarification or this is not an examination.