Summary: No, the dead cannot help us. Ecclesiastes 9:5 (NASB), “the dead do not know anything.” 

Explanation: Jesus said death was like sleep. When Jesus's friend, Lazarus, was sick, the family asked Jesus to come and heal him. But Jesus was busy. Finally, when He did decide to go to his friend, Jesus said, “Our friend Lazarus sleeps, but I go that I may wake him up. Then His disciples said, Lord if he sleeps he will get well. However, Jesus spoke of his death, but they thought that He was speaking about taking rest in sleep. Then Jesus said to them plainly, Lazarus is dead,” John 11:11-14 (NASB).

The Apostle Paul also said death was like sleep in 1 Thessalonians 4:13 (NIV), “Brothers and sisters, we do not want you to be uninformed about those who sleep in death, so that you do not grieve like the rest of mankind, who have no hope.” Christians know Jesus will wake everyone from the sleep of death in the resurrection. Therefore we do not grieve as others, because we know our loved ones will live again! (See John 5:28, 29.)

But can the sleeping dead help the living now? No. The dead know nothing. Ecclesiastes 9:10, “…there is no work or device or knowledge or wisdom in the grave where you are going.”

Who does help the living? God and Jesus! Jesus instructed His disciples, “Most assuredly, I say to you, whatever you ask the Father in My name He will give you.” John 16:23. And of course, we always need to pray that God's will, not our wills, be done with every request, (Matthew 26:39).

The Bible never teaches anyone to pray or speak to the dead – only to God.