It would be a very good idea for you to get it sorted out and prepare and file your tax returns. First---get your ducks in a row--get all of your income for each tax year sorted out----W-2's, 1099's, etc. etc. Each tax year has to be prepared separately using the forms for the specific tax year. Do not try to combine them in any way---not even in the same envelope when you mail them.
You do not say how far back you need to go. TurboTax software is available for 2017, 2018 and 2019---and of course for 2020. If this is too complex you might need to seek local paid tax help.
The current online program can only be used for a 2020 return--no other year. And if you did not file a 2019 return you will have trouble e-filing 2020. When it asks for your 2019 AGI try using zero. If zero does not work then you have to print, sign and mail 2020.
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)
https://turbotax.intuit.com/personal-taxes/past-years-products/
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.
Refunds for tax years 2016 or earlier have been forfeited and will not be paid to you even if shown on the tax return form. But if you owe tax due, you will still have to pay, and you will be billed later for the interest and penalties owed.
If your returns are simple enough you could also prepare them on paper by hand:
PRIOR YEAR FORMS FROM IRS
2016
Form 1040 https://www.irs.gov/pub/irs-prior/f1040--2016.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
Form1040EZ https://www.irs.gov/pub/irs-prior/f1040ez--2015.pdf
Form1040EZ Instructions https://www.irs.gov/pub/irs-pdf/i1040ez.pdf
https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
Remember to prepare your state return as well—if you live in a state that has a state income tax.
2017
https://www.irs.gov/pub/irs-prior/i1040gi--2017.pdfhttps://www.irs.gov/pub/irs-prior/f1040--2017.pdf
https://www.irs.gov/pub/irs-prior/f1040a--2017.pdf
https://www.irs.gov/pub/irs-prior/i1040a--2017.pdf
https://www.irs.gov/pub/irs-prior/f1040ez--2017.pdf
https://www.irs.gov/pub/irs-prior/i1040ez--2017.pdf
2018 Form 1040, Schedules and Instructions
https://www.irs.gov/pub/irs-prior/f1040--2018.pdf
https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf
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
0
2019
2019 Instructions
https://www.irs.gov/pub/irs-prior/i1040gi--2019.pdf
1040 https://www.irs.gov/pub/irs-prior/f1040--2019.pdf
1040SR https://www.irs.gov/pub/irs-prior/f1040s--2019.pdf
2019 Schedules 1-3
https://www.irs.gov/pub/irs-prior/f1040s1--2019.pdf
https://www.irs.gov/pub/irs-prior/f1040s2--2019.pdf
https://www.irs.gov/pub/irs-prior/f1040s3--2019.pdf
W-2's come from your employer, You might need to phone, drop in, email and/or snail mail an old employer to make sure they know where to send your W-2.
https://ttlc.intuit.com/questions/2561916-how-can-i-get-a-copy-of-my-w-2
Other ways to get W-2’s:
Pay Social Security $90 per W-2:
You can get a wage and income transcript from the IRS: It will not show the actual W-2, 1099’s, etc, but will show the income information the IRS received. It will not, however, show your state information. It will only show the federal information.
https://www.irs.gov/individuals/get-transcript
There are over a dozen kinds of 1099's. A 1099Misc is typically issued by an individual or business for whom you performed work as an independent contractor, so seek a copy from them if you did not save yours. Many of the other types of 1099's are issued by banks, brokerages and other financial institutions from which you can seek copies.