I presume your talking about a timber door. What must be wrong is the spindle that runs through the lock and sits into both handles is too short. It will probably have been like this for years but with you taking it the spindle will have positioned itself further into the inside handle not allowing it to be operated from the outside. Either buy a longer spindle, or pack off the inside of the handle where the spindle sits with a small piece of cardboard to stop it from sitting into the handle too deep.
Scott
August 2007