How to load a .mat file, corresponding to a .txt file, as per user input?

I have .txt files in my Matlab directory in the format PhasexxSubjectyy.txt, where xx and yy denote integers. How do I take inputs from the user for xx and yy, and load the respective .mat file? I also need to display the mean and standard deviation of the data as a part of the .mat file. How to do that? I am a beginner and this is urgent!

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency