By default, TurboTax saves your tax data files in the Documents folder on your computer. The specific folder location is
C:Users<user_name>DocumentsTurboTax<YYYY>, where <user_name> is your Windows username and <YYYY> represents the tax year.
For example, Alex Smith is looking for a 2018 tax return and Alex's Windows username is asmith. If Alex saved the tax return to the default location, it'll be located at
C:UsersasmithDocumentsTurboTax2018. To open a tax return, double-click the corresponding tax data file.