God can change anything through prayer according to His will
"Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God; and the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus."(Php. 4:6-7)
Prayer changes things only for God's people because "all things work together for good to those who love God, to those who are called according to His purpose." (Rom 8:26-28). "Everything by prayer" does not mean everything in the universe, but rather "all things that pertain to life and godliness" (2 Pet. 1:3-4, 11). The "life" refers to eternal life. We pray only for the change that has connection to God's plan of salvation.
However this does not mean that we pray only for spiritual things. Prayer will certainly change material things when that change has a spiritual value and benefit.
Prayer is not for satisfying physical and material lusts (Jas 4:3). It does not mean that we cannot pray for material needs. Jesus taught us to pray, "Give us each day our daily bread and forgive us our trespasses..." (Lk. 11:3-4) The main purpose of prayer, however, is to help make things "turn out for salvation" (Php 1:19).
"The effective, fervent prayer of a righteous man avails much." (Jas 5:16) When a righteous man prays there are more changes than he could ever imagine or comprehend. "And the prayer of faith will save the sick, and the Lord will raise him up. And if he has committed sins, he will be forgiven." (Jas. 5:15) The sick person is not only healed but also saved.
Malaysian Woman received Holy Spirit and Healing through Prayer
Many years ago there was a Christian woman in Kuala Lumpur, West Malaysia who had been suffering from hemorrhaging, the sickness similar to the one who touched the border of Jesus' garment and was healed (Lk. 8:43-48). This Malaysian woman had also spent her family's savings on doctors and still could not be healed. A member brought her to our church and after hearing the full gospel of salvation she believed in the new birth of water and the Spirit (Jn. 3:3-8).
One evening while she was praying fervently at home she was filled with the Holy Spirit and spoke with tongues. At that moment she also felt the power of God descended on her and pushed some liquid out of her body. After the prayer she got up and saw a puddle of blood on the floor where she had been kneeling. This woman was completely healed from that moment onwards. She and her husband were baptized into the Lord Jesus Christ.
After many months she met one of her former physicians at the town market. The doctor was surprised that she looked so healthy and asked what happened to her. He also wanted to know who had healed her. She said her doctor is the Lord Jesus Christ. The doctor also believed in Jesus and was baptized into Him.