OK ... you have a big mess to clean up. Once the IRS processes the incorrect 2019 return only then can you amend the 2019 return. If you are lucky they will refuse the 2019 return and that would be perfect.
Now for the other tax years ... you still have to really file the 2018 return and you can do so now ... you do not need to wait for the 2019 error to be corrected. The 2015 tax year is no longer supported so you will either need to get the forms from the feds/state off their website OR seek local professional assistance. Also any refund from 2015 is now forfeited but if you owe you still need to filed and paid.
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.
This link Where can I obtain authentic TurboTax software? has a list of authorized TurboTax resellers.
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.
