Mathcad 15.0 No Longer Working

I have attempted, but failed, to authorize my Mathcad 15.0 program. Is there anything that can be done to make this program work? If not, is it possible for me to upgrade to a current version and get credit for the Mathcad 15.0 that I already purchased?

I am in urgent need of the use of this program. Anything that can be done to expedite getting this corrected would be appreciated.

Thanks!