To file previous years taxes TurboTax, first, ensure you have the software for the specific tax year you want to file. If you don't have the correct version, you may need to purchase or download it from TurboTax's website. Once installed, open the software and select the option to start a new return. Enter your personal and financial information, and input your income and deductions for the relevant tax year. TurboTax will guide you through the process, helping you complete the necessary forms and calculations. After reviewing your return, you can file it electronically or print and mail the paper copy to the respective tax agency. Keep in mind that there may be additional fees for filing late returns, and it's advisable to consult with a tax professional if you encounter any complexities or uncertainties.