mortise lock - latch bolt stuck

Answer 1

 The k***s don't need to be loosened.  The spindle does.  Unsrew and pull off the k***s. pull out the spindle that the screws were screwed onto.  The spindle is in two pieces screwed together in the middle.  unscrew half turn and s***w everything back togehter and retry.  I still doen.t work repeat until it works.  If yu are not successful the copper/brass pij spring may be out of position in the lock.  If yes then take it to a good hardware store where somewone camn help reattach.