For the music director; a psalm of David. 

David wrote this song for the music director of the Levitical chorus.

13:1 How long, Lord, will you continue to ignore me? How long will you pay no attention to me? 

David asked Jehovah how long that he would be ignored.

13:2 How long must I worry, and suffer in broad daylight? How long will my enemy gloat over me? 

How long must David worry and suffer? How long will the enemy gloat over David?

13:3 Look at me! Answer me, O Lord my God! Revive me, or else I will die! 

David asked Jehovah to look closely at his situation. He asked God to revive him, or to give him divine wisdom. If God refused to give him divine wisdom, then David would die. This was a life-and-death prayer request.

13:4 Then my enemy will say, “I have defeated him!” Then my foes will rejoice because I am upended. 

If Jehovah does not help David, then David’s enemies will boast and rejoice that they defeated the Lord’s anointed.

13:5 But I trust in your faithfulness. May I rejoice because of your deliverance! 

David trusted in Jehovah’s חָ֫סֶד (hesed), or faithful covenant love.  David was protected by the Davidic Covenant. David carried the messianic seed. David rejoiced, because he knew that God would deliver him from his enemies.

13:6 I will sing praises to the Lord when he vindicates me. 

David will sing praises to Jehovah when he is rescued out of this life and death situation. David usually went to the city gates to publicly sing these praises.