TurboTax software for any year earlier than 2020 is no longer available nor would it be supported or updated even if you can find it on eBay, etc. You can seek local paid tax professional help for those past years. And...if you really mean you have business returns for an Scorp, Ccorps, etc. you face significant penalties for failure to file. If you have had self-employment income, you will also face late filing penalties and will owe interest on any tax due. Using a professional will be helpful since they will be in a better position to help you negotiate with the IRS.