if prior to 2016 TT will be of no help since those years are no longer supported. it really would be easier to use the same source you used to prepare the original return since all the data except for the changes already exist. but if you want to go the TT route online is only available for 2019. for years 2016-2018 you would need to purchase and install the desktop software. if necessary you would also have to purchase the state.
https://turbotax.intuit.com/personal-taxes/past-years-products/
after you get the software you would need to enter all the info from the original return so the TT numbers come out exactly as originally filed. how much detail depends on what you are going to amend.
