We understand that you feel disappointed and that your prayers weren't answered in the way or timing you expected. It's important to remember that God's timing is not always the same as ours, and His ways are higher than our ways.
Firstly, let's consider that God's lack of response in a certain time does not mean no response.
Delight yourself also in Yahweh, and He will give you the desires of your heart. Commit your way to Yahweh. Trust also in Him, and He will do this: He will make your righteousness go forth as the light. Psalm 37:4-6 WEB
Above all, you need to know that never too late to return to God and that the deadline is not past to be reconciled to God. God's time is always now.
Behold, now is the acceptable time. Behold, now is the day of salvation. 2 Corinthians 6:2b WEB
However, we must also address that prayer must be directed to God the Father In the name of Jesus Christ to be effective. It is only by the name of Jesus that we have access to God. Also, there is no other name by which we can be saved.
There is salvation in no one else, for there is no other name under heaven that is given among men, by which we must be saved!" Acts 4:12 WEB
If you mean that the prayer was not answered because it was not in Jesus Name, we emplore you to return to use the name of Jesus in your prayers. However, even though that is essential, that would not be necessary for God to save you again. Salvation is a ever continuing relationship and does not need to be repeated, only returned to. You do not have to but can admit that you went away and confess with your mouth that Jesus Christ is Lord.
that if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised Him from the dead, you will be saved. For with the heart, one believes resulting in righteousness; and with the mouth confession is made resulting in salvation. Romans 10:9-10
For, "Whoever will call on the name of the Lord will be saved." Romans 10:13 WEB
No matter how far you stray from Him, God is always ready to welcome you back with open arms, just like the parable of the Prodigal Son in Luke 15:11-32.
Let's pray together:
Dear Heavenly Father,
We come before You in the name of Jesus Christ to lift up our brother Dexter2020. Lord, we pray that You will reveal Yourself to him again and reassure him of Your unfailing love. Help him to trust in Your timing and to understand that You are always working for his good, even when it seems like nothing is there. We pray that You will guide him back into a strong relationship with You, and that he will delight himself in You, trusting that You will give him the desires of his heart as You did in sending Jesus for all us. Help him to commit his way to You Lord.
In Jesus Christ's name. Amen