DND has to be enabled for the Silence portion to work. See here --> Use Do Not Disturb on your iPhone, iPad, and iPod touch ...
Queen1994 wrote:
My phone will not send an audible alert when it is locked.
Either I am unable to understand your query or there is something amiss here in your post. I am referring to the "In general". Is it that you are not getting alert sound in general (for all apps) only while the iPhone is locked? Otherwise you are getting sound alerts!
If my above statement is true then, please, get a Genius Bar Reservation and Apple Support Options - Apple