Have you previuosly trained your dog for this and now he is ignoring it? I am going to assume he has been taught before and needs re-enforcement.

I would start by puttin ghim on a long line ( about 20-30 ft. Let him get interesting in somthing and say his name, come. If he doesn't immmediatley turn and come to you, start reeling him in. do not repeat the command, just make him to it. Then reinforce ( give treats, tell him good dog, etc, etc) Do this a few times and hopefully you will nothave to reel him in. up the criteria...oinly give him treats if he comes on his own....Start not giveing treats every time, but always praise him. In crease the distractiona dn the length. He should get better at it!