Psalms like chapters 42 and 43 make the Bible real. It helps us to see that it is not this idea that God will get rid of all the sorrow and hard times in our lives. It also shows us that there is a place in our circumstances where even the best of believers come to a place of questioning God. But in the middle of the questioning and hardship we are encouraged by the Psalm to encourage ourselves, confide in God and put our hope and trust in Him. We are to remind ourselves that whatever may happen we can trust God to work it out for the best possible outcome for our lives.
In our lives we will experience sorrow, pain, anguish, angst, heartbreak - in those moments it is natural to question God and sometimes even feel like He has abandoned you. But in the end the best course of action is to turn to God - to put your hope and trust in Him, because He is the all-mighty, powerful, loving, merciful, faithful, (and the list goes on) God.