Blender 2.79b Grease pencil brush hotkeys not working (Windows7 ,64bit) So,while using Blender 2.79b Grease pencil brushes  (on Windows7 ,64bit) , I tried using the number (1,2,3....)default hotkeys assigned to them  and found they were not working.Then I changed the hotkeys to other unique keys so that they didn't match with other operators  still the brush hotkeys where not working.
Any solution?
Finally ,there were some old files from previous versions of blender lying in Program files directory.Deleting them and reinstalling blender worked and now grease pencil shortcuts work.