Log out first then edit it, then log in again. Or, stop the server, edit, and restart.
<talkaction log="yes" words="/m" access="4" event="script" value="creature.lua"/>
Goto talkactions.xml
you will have something like this.
and this is the id: access="4"Code:<talkaction log="yes" words="/m" access="4" event="script" value="creature.lua"/>
Also ingame you could do one of these. /commands, /cmd, !commands, !cmd