Environment path varibles the function keys are not working?

Hi... suddenly the three keys are not working in the allegro PCB editor env. So can anyone help me how to edit the files specified in the env path. Tell me briefly how to edit the env path editor and how to link it with the Allegro PCB editor. The Function keys are Zoom in (i), Zoom fit(f), Slide (f3), these keys are independently assigned edited in env file. But suddenly today morning onwards this keys are not working. Thanks & Regards Dhamodharan