Can I get Mathcad 14.0 for free? Or Mathcad Express is the only option left? On addition I would like to say that I am a student of Civil Engineering.
The problem is, that Mathcad Express does not open the .mcd files.
The only free version is Mathcad Express (Prime).
You can get a 1 month trial of Mathcad 15 here: http://www.ptc.com/engineering-math-software/mathcad/free-trial
You can purchase a student edition (discounted) of Mathcad Prime; and with any purchase of Mathcad Prime, you get Mathcad 15 for free (same download as above, but point the license wizard to your Prime license instead of the free trial info).
To open .mcd files, you need Mathcad 15 (or earlier).
With both Mathcad Prime and Mathcad 15 installed, you can convert .mcd and .xmcd files (legacy files) to .mcdx files (Prime files).
As noted by Valery, you could also post files here requesting someone convert them for you.
Note that there is no backwards compatibility from Prime to the legacy editions, so if you need to collaborate with a user of a legacy edition, you don't want to convert the files to Prime.
You can download a free evaluation version of Mathcad 15, which should open any Mathcad (not Prime) .MCD or .XMCD file here: Thank You for Your Interest in PTC Mathcad 15 | PTC
Prime has a utility to translate Mathcad (not Prime) files to Prime's format; it requires Mathcad 15 to be installed. You should be able to use the Mathcad 15 evaluation version for that.
Note that Mathcad (15 and before) has capabalitities that Prime does not support, so the 'quality' of translation, if it works at all, is badly predictable.