I have pro audio 8 cakewalk software.  I use this for midi files that I purchase and use the software to play them through.  I have a compaq laptop that has Microsoft xp.  I was playing them yesterday and everything was fine, no issues.  Today I go to play my midi files and I am getting no sound.  I can see the midi files playing but no sound coming from my laptop.  If I put a cd in or do anything else, my sound is working, just not when I'm trying to hear my cakewalk files.  I did not change any settings and really need an answer because I need to use these files tomorrow.  Any help would greatly be appreciated.

I just postec about the pro audio 8 and no sound coming from my purchased music files.  I am also seem to be having issues when I am playing a cd through the microsoft media player, it is locking up.  Looked an saw that my sound device in Pro audio is also microsoft related.  Could it possibly be my driver for this?  Sorry I far from being a technical person, just reaching here.
 

As MIDI has no sound, it's only control data (like digital sheet music), the answer lies in what is producing the sound. Talking about Pro Audio, I guess you are using the built in Wavetable synth? Check that the MIDI is routed to that.
My guess is your CD-player is just coming to the end of its life.