Cant use shorcut for sub-object selection

[khoahuynh]

I've just met quite a simple problem but it's been annoying me lately

I can't press the number button ( 1,2,3,4,5,6,...) for switching between the selection for vertex, edges, elements,... when I use max for a few minutes (maybe I mistakenly pressed some button)

I'm using 3dsMax 2013 64bits

Another thing is that can you guys tell me how to change from pressing 6 to quit from sub-object selection by just pressing the same number for current sub-object selection.