Psalm 66
All nations should praise God - if you are having trouble praising God today. I would suggest that you take a moment to look back over your life. Take a moment to to see the great and wonderful things God has done for you - the answered prayers, the doors opened, the many times that "He Blocked It". Your "it" may be different from my "it", however, I am sure that God has protected you from "seen and unseen". How wonderful!
66:20 - Blessed be God, which hath not turned away my prayer, Nor His mercy from me.