I went to church growing up and was baptized at 9 years old, but as I got older along the age of 13 or 14 I started hanging around the wrong crowds and doing things that I knew I should not do. I convinced myself in my head that everything is ok I will have to get "right" again hopefully before I die or before Jesus returns. I know now that this was wrong and dangerous to do. I was reading my bible about 2 nights ago and came across Hebrews 10:26. My question is Do I still have the chance of being saved and serving Jesus and going to Heaven or am I basically going to Hell no matter what?
The passage to which you refer reads, in its context:
And let us consider one another to provoke unto love and to good works: Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching. For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries. (Hebrews 10:24-27)
The context is building one another up, including encouraging assembling with the church. The verse you ask about begins “For” if we sin wilfully. That means that it is referring back to what was just said. Willful, or willing, sin relates to voluntarily choosing to avoid contact with members of the church.
Your question is whether such a choice cannot be forgiven. The verse does not say this. As long as you choose to sin, then you are rejecting the forgiveness through the death and resurrection of Jesus. If you choose to turn back to God, then you are no longer sinning wilfully, and the sacrifice again becomes effective in your life.
Basically, one of the conditions of forgiveness is that we acknowledge our sin. God never promises to forgive sin if somebody doesn’t seek forgiveness. While you were following the wrong crowd (read Proverbs 1-6 for advice about that) you chose not to seek forgiveness, and so you rejected the sacrifice for sin. If you return to God, the sacrifice remains. It is not that the sacrifice went away; it is always available. It is that you went away from it. “For if we walk in the light, as he is in the light, we have fellowship with one another, and blood of Jesus Christ his son continually cleanses from all sin.” When you walk in darkness it doesn’t cleanse; when you return to the light the cleansing power is still there.
I hope this puts your mind to rest. I also pray that it will prompt you to return to following God.