I am trying to prepare prior years 2014 and 2015

[jerry2000]

Turbotax Online works only for current year (2016) taxes, and not for any other year.
If you want to use TurboTax for any other year you will need to purchase the Desktop Version for each year that you need to file. You can do that at this link:
http://shop.turbotax.intuit.com/personal-taxes/past-years-products.jsp

You can download the Forms and Instructions free from the IRS web site at this link:
http://www.irs.gov/app/picklist/list/priorFormPublication.html

In any event, you have to file the return by mail. Turbotax does not support e-file of prior year returns. Tip: If you prepare multiple years of prior returns, mail each one to the IRS in a separate envelope to be sure that each one is recognized as a separate tax return.

[retiree]

You can no longer prepare (or continue) a tax return for 2015 (or earlier) on-line; also the IRS is
no longer accepting e-files for 2015 (or earlier returns). 

Returns for previous year(s) MUST be PRINTED and MAILED.  Only the current tax year 2016 can be prepared on-line; only the current tax year 2016 can be e-filed, after the IRS begins accepting e-files late in January 2017.

You can purchase the Desktop version of TTax for previous years at the link below and install it on your own computer.

Previous years' TTax
http://turbotax.intuit.com/personal-taxes/past-years-products.jsp

EVERY YEAR  TTax shuts down the servers for the on-line version in mid-October to prepare for the upcoming 2016 tax
filing season.  At that time any on-line return that had not been printed, e-filed (successfully),
or paid for was erased.  (This has been TTax's policy for many years.)

SPECIAL NOTE:
If you are preparing tax returns for more than one year, DO NOT mail the returns in the same envelope --the IRS will likely get them mixed and cause delays.  Also, when mailing tax returns it is a good idea to mail the returns 'Certified' with 'Return Receipt' so that you will have proof of submission.