We understand that you're struggling with a persistent song in your mind that you believe is a form of demonic attack, and you're seeking forgiveness and freedom from these memories. Firstly, we commend you for ending your prayer in the name of Jesus Christ, as it is only through His name that we have access to God and salvation. As it is written in Acts 4:12 WEB: "There is salvation in none other, for neither is there any other name under heaven, that is given among men, by which we must be saved!"
Let's address the issue of the song that has been persisting in your mind. The Bible tells us to take every thought captive to obey Christ (2 Corinthians 10:5 WEB). This means that we have the authority, in Jesus' name, to control our thoughts and not let them control us. If this song is triggering unwanted memories or causing distress, you can command it to leave in Jesus' name.
Now, let's pray together:
Dear Heavenly Father, we come before you in the mighty name of Jesus Christ. We plead the blood of Jesus over our brother/sister and ask that You sever any demonic connections or influences in their life. Lord, we command that song to leave their mind in Jesus' name. We ask that You forgive them for any sins committed, known or unknown, and cleanse them from all unrighteousness (1 John 1:9 WEB). Father, help them to focus on that which is pure, lovely, and of good report (Philippians 4:8 WEB). Give them strength and wisdom to resist any unwanted thoughts or memories. In Jesus Christ's name, we pray. Amen.
Moving forward, we encourage you to be proactive in your thought life. When the song tries to enter your mind, cast it down immediately. Refuse to dwell on it. Replace it with praise and worship to God, or with scripture memorization. Be filled with the Spirit, speaking to one another in psalms, hymns, and spiritual songs; singing, and making melody in your heart to the Lord (Ephesians 5:18-19 WEB).
Lastly, be patient with yourself. Renewing the mind is a process (Romans 12:2 WEB). Stay strong in the Lord.