If you are having trouble importing your W-2, it's possible that your employer is not a TurboTax Import Partner. You can find a list of TurboTax Import Partners here https://www.partner.turbotax.com/top_partner_list.html
NOTE: If your employer is a Partner, your W-2 must be available for import – most are ready by February 1. Employers have until January 31, 2017 to issue W-2's.
Otherwise, you can see see steps below for how to manually add a W-2:
https://ttlc.intuit.com/replies/4712124