UA-25 no sound through phones...

Hi Folks,
 
 
got a problem, hoping someone can help because I am stumped!!!!
Until last thursday, I was hearing all my recorded midi and audio files through my UA-25 interface but since thursday afternoon, it will not play a thing through them! If I plug in my guitar, I can hear it but if I press record and try to record some lead over what I've already recorded, the recorded files do not play! If I just click play without recording any new guitar, I cannot hear any sound out of the interface...
I have checked that there is output from the UA-25 on the computer settings and there is but as soon as I try to record/play the recorded files, there is no sound!
 
Any advice would be useful...
 
Oh, and yes I have checked for foreign debris in the input hole and no there isn't any...
 
:o)