I left the lord years ago and became an atheist, even blasphemed.
I'm trying to get back with the lord but can't repent from the heart anymore. My faith is no more, the bible and sermon no longer makes sense.
Have i commited the unpardonable sin? How do i know?
No you have not committed the unpardonable sin! But you have been attacked the Satan. There was some confusion in your understanding of the gospel of Christ, and Satan took advantage of that by convincing you to turn away.
Matthew 12:31 KJV is to the Jews. Jesus had not died on the cross at that time to offer forgiveness for sins.
The fact that you are speaking about it and are concerned shows you have not lost your salvation. Plus a true Christians cannot loose their salvation. Whether you see it or not, your heartfelt expression of concern for what you did shows you have repented already.
Healthy guilt is from the Holy Spirit Who pricks our heart. Plus, the Bible tells us there is no condemnation in Christ Jesus, Romans 8:1 KJV. Also, once we come to Christ, God does not let us go because God Has predestinated us, Ephesians 1:5 KJV, Romans 8:30 KJV, and is in control of each believer’s salvation path by working in us to His good pleasure, Philippians 2:13 KJV.
We might think we walked away, but the Holy Spirit guides us back.
Don’t worry whether you have repented or not. God permits repentance - and your turning around, confessing, and expressing concerned and worry shows a repentant heart.
It’s possible you will become a powerful servant for God, and Satan knows it, which is why you were attacked so drastically. We are told we wrestle not with flush and blood, and to put on the whole armor of God, Ephesians 6:12-13 KJV.
When you open your Bible and start to read, bow your head and pray and ask your guide to help you - trust your guide, the Holy Spirit.
God bless you! You are greatly blessed, that’s why you were attacked. Count it all joy when we fall in divers temptations, James 1:2-3 KJV