I had a side business two years ago but last year I didn't do anything with it (no expenses, no income) how do I report this correctly?

If you have had no business activity you do not have to file a tax return for the business.  Common business activities that would require you to file a tax return include; reporting income, expenses, depreciation, sale of business property or the sale of the business.

If you are closing or have closed your side business the link Closing a Business will take you to a TurboTax page that has useful information and links to assist you with the closing of your business.

If your business has assets and/or inventory, then even though the business may not have had any income or expenses during the tax year, you can expect to get a nasty gram from the IRS 24-36 months after the filing deadline, asking you for the SCH C to show either the depreciation of those assets, or the disposition of those assets.