2014 thru 2016 can't be done on TT since the software is no longer available, 2017 thru 2019 must be purchased. they only work on a full PC or MAC. they can't be e-filed. 2020 can be done online
any refunds due for years prior to 2017 are no longer refundable
You are trying to take on a major project. Does your dad have the income and other tax documents necessary to prepare those returns? Does he have W-2's, 1099's, etc. etc. etc.?
He cannot get an income tax refund for any tax year earlier than 2017. Refunds for earlier years have been forfeited. But if he owes tax for those years --- it is still owed with penalties and interest.
As Champ Mike9241 said, software is not available for years earlier than 2017. You could use the paper forms and prepare them by hand to mail in.
If this is a real mess, then seek local paid tax help. If your dad owes a lot of back tax, a pro might be able to negotiate with the IRS.
But if you want to tackle it:
Online preparation and e-filing for 2017, 2018 and 2019 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2017, 2018, or 2019 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.
Remember to prepare your state return as well—if you live in a state that has a state income tax.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.
Federal and state returns must be in separate envelopes and they are mailed to different addresses. Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile device.
If you are getting a refund, there is not a penalty for filing past the deadline. If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.
Form1040 Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2015.pdf
Form 1040A Instructions https://www.irs.gov/pub/irs-prior/i1040a--2015.pdf
Form 1040EZ Instructions https://www.irs.gov/pub/irs-prior/i1040ez--2015.pdf
Form 1040 Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2016.pdf
Form 1040A https://www.irs.gov/pub/irs-pdf/f1040a.pdf
Form 1040AInstructions https://www.irs.gov/pub/irs-prior/i1040a--2016.pdf
Form 1040EZ Instructions https://www.irs.gov/pub/irs-pdf/i1040ez.pdf
2018 Form 1040, Schedules and Instructions
2018 Tax and EIC Tables https://www.irs.gov/pub/irs-prior/i1040tt--2018.pdf
IRS 2018 Schedules 1 thru 6 (only if needed)
Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2018.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2018.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2018.pdf
Sch 4 : https://www.irs.gov/pub/irs-prior/f1040s4--2018.pdf
Sch 5 : https://www.irs.gov/pub/irs-prior/f1040s5--2018.pdf
Sch 6 : https://www.irs.gov/pub/irs-prior/f1040s6--2018.pdf
2019 Schedules 1-3