Here is a quote from "Mathcad Prime 2.0 Read This First":
"You must have Mathcad 15.0 M010 or later to convert worksheets that you created in
previous releases of Mathcad to Mathcad Prime 2.0. You cannot open previous Mathcad
worksheets directly. You must convert them using the Mathcad Prime 2.0 XMCD,
MCD Converter button on the Input/Output tab in Mathcad Prime 2.0. You can also
access the XMCD, MCD Converter from the Windows Start menu."
Mathcad 15.0 30-day free trial download can be found here: http://www.ptc.com/products/mathcad/mathcad-15-0/free-trial.htm
You can read about installation and licensing process for Mathcad 15 and Prime 2.0, here: http://blogs.ptc.com/2012/03/01/mathcad-licensing-part-3/
P.S. Also, you can attach the necessary Mathcad 14 files to the message and I will convert them into a format MCDX format (Mathcad Prime file format).