I've used turbo tax from the start, last filed 2015; I need to access or to purchase premier software downloads for tax years ending 2016 through 2019. Please help
Sorry the don't sell 2016 anymore. They only sell the last 3 years. Buy 2017-2019 here
https://turbotax.intuit.com/personal-taxes/past-years-products/
For 2016
You might want to go to a local accountant or tax place if you have a complicated return. For simple returns you can fill out the forms by hand.
You can fill out the blank forms for free.
Here are some blank forms & instructions for 2016
1040 https://www.irs.gov/pub/irs-prior/f1040--2016.pdf
Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2016.pdf
1040A https://www.irs.gov/pub/irs-prior/f1040a--2016.pdf
Instructions https://www.irs.gov/pub/irs-prior/i1040a--2016.pdf
1040EZ https://www.irs.gov/pub/irs-prior/f1040ez--2016.pdf
Instructions https://www.irs.gov/pub/irs-prior/i1040ez--2016.pdf
2016 Tax Tables https://www.irs.gov/pub/irs-prior/i1040tt--2016.pdf
Publication 17 Tax Guide for 2016 https://www.irs.gov/pub/irs-prior/p17--2016.pdf
Another thing you need to be aware of is that you are too late to receive tax refunds for 2016 or 2017. If the tax return form shows a refund, you forfeited it already because it is too late. But if you owe tax for those years you still need to pay, and will be subject to late penalties and interest. When you get so many years behind in filing your tax returns, it might be a better idea to seek a local paid tax pro to help you.