How can I access my W2's from 2015?

TurboTax does not have a copy of the W-2.  It would have a Wage and Tax Statement worksheet that emulates a W-2 and is populated with your entries or the imported information.  The worksheet would be included in the PDF of the tax return if you downloaded the PDF to include All forms and worksheets in the tax year the return was completed.  

If you cannot obtain the W-2 from your employer, then for a fee of $37 you can get a complete copy of a W-2 from the Social Security Administration - https://faq.ssa.gov/ics/support/KBAnswer.asp?questionID=3836

You can get a free Wage and Income transcript from the IRS by completing a Form 4506-T (however it will not have the state information on it) - http://www.irs.gov/pub/irs-pdf/f4506t.pdf

See this IRS website for transcripts - http://www.irs.gov/Individuals/Get-Transcript

For a fee of $50 you can get a complete federal tax return to include copies of W-2's from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf

See this IRS Tax Topic - http://www.irs.gov/taxtopics/tc159.html

Go back into 2015 tax returns that were saved, and print them out.