if you didn't file, the IRS can still go after you if you owe. If you're due a refund, forget it. the 2015 return had to be file by 4/15/18. if you have a different issue post it.
https://ttlc.intuit.com/questions/3404575-how-do-i-access-my-prior-year-2017-return
You can get a free transcript from the IRS:
https://www.irs.gov/individuals/get-transcript
How do I get a copy of a return I filed using online TurboTax?
https://ttlc.intuit.com/questions/1900748
How do I get a copy of a return I prepared using desktop TurboTax?
https://ttlc.intuit.com/questions/1900639
Note: Every year, before mid-October, print a copy of your current year tax return and save it as a tax file and pdf, too. That way you will have it when you need it for school, a loan, next year’s tax return, etc. without going through a lot of aggravation (and expense) to get it.
https://ttlc.intuit.com/questions/1912544-how-do-i-save-my-2018-turbotax-online-return-as-a-pdf