unless you use a professional you'll have to manually prepare returns for 2013-2015 since software is no longer available. you can find this software in the web, but it is not updateable and likely to produce an incorrect return. if you are due a refund for those years, you won't get it because you have filed past the statute of limitation. if you owe, expect to pay penalties and interest besides the taxes.
there may be reasons to file those returns even if there is an overpayment (which you won't get) such as loss carryforwards which will be lost if you don't file.
you have to buy separate software for each year 2016 - 2018. (2018 can no longer be prepared online) make sure your computer can run the software and be sure to get the right version depending on whether you have a PC or MAC.
start with the earliest year. this will allow transfer of certain data to the next year.
You need to start with the oldest return first. TurboTax only supports their software for the current tax filing year and 3 years back. So the farthest back you can go with TurboTax right now is the 2016 tax return. For earlier years you'll need to get the blank forms from the IRS website and do them manually yourself, or seek professional help.
Even if you can get TurboTax for years prior to 2016, you can not get the *REQUIRED* corrections and updates to the program. So chances are high the return would be wrong anyway. TurboTax does not and will not honor their 100% accuracy guarantee for tax years prior to 2016 either. Additionally, if you are due a refund the IRS has a 3 year statute of limitations on that. So any refunds due for tax years 2015 and prior will not be paid.
Finally, a prior year tax return can not be e-filed. The IRS says so. You have to print, sign and mail it to the IRS.
I need to do 2018 return with you.
I did my 2019 return yesterday.
I have simple Retire with spouse,
SSA 1099 benefit statement 2018.
I have no enether income or expenses.
I don't have 2017 and 2018 return because I haven only 1099 earn income only so I didn't file 17 and 18 return.
Now I like to file.
I did 2019 ol ready.
TurboTax prior year software - https://turbotax.intuit.com/personal-taxes/past-years-products/
IRS website for prior year forms, schedules and instructions - https://apps.irs.gov/app/picklist/list/priorFormPublication.html
Oldest first. All prior year returns have to be printed and mailed, they cannot be e-filed.