Prayer works, we just need to continue and not give up.  This is called perseverance in prayer. The prayer of Elijah, which stopped the rain from heaven and later opened heaven’s floodgates, was an example of a long series of his mighty prayers and pleadings with God. If we Christians would remember that perseverance in prayer is necessary for it to be effective and victorious!

James 5:16 … pray one for another, that ye may be healed. The supplication of a righteous man availeth much in its working. 17 Elijah was a man of like passions with us, and he prayed fervently that it might not rain; and it rained not on the earth for three years and six months. 18 And he prayed again; and the heaven gave rain, and the earth brought forth her fruit.

Prayer and hope in God is a great thing.