I keep having these dreams periodically over the past year that I pass away in a car accident.. and then im at my house (sort of as a spirit), and I am constantly walking around in my house and trying to reach out to my family... but they can't see me. I keep trying to tell/show them where I hid things of value because they are struggling, and I keep trying to move things or touch things to help them but I can't. I stand in front of them waving my arms, trying to break things, cry and scream for them to try to hear me or see me, but it doesn't work because I can't physically touch anything and they can't hear me. Whenever I wake up after this, its like the most peaceful feeling in the world like I was really dead or something in my sleep and I couldn't really feel anything.. but I dont understand why I am having these dreams or what they mean. Any thoughts?

I'm a guess what you could call an opposite dreamer of this dream. It may help with your dreams though. I lived with my grandparents until my grandfather died when I was 12. my point being, I kept having this terrible dream that my grandfather would die. It was my worst fear. He died that same year on our front lawn from a massive heart attack at 57! Premonition?? Or my worst fear seeping into my dreams?? I'll never know.
Every since then I have these dreams, even now, that he has something he wants me to find. I'm frantic in my dreams looking for I don't even know what. Running around our old house or land, then I SEE him. He smiles and starts walking away,I follow him util he disappears. A calm goes over me. He never speaks to me and I know in the dreams that he's not allowed too. I'll never find what I'm looking for.
Maybe you have a fear that if something happened to you, your loved ones would not be able to handle things. it might help if you wrote down the important things you would want your family to know about. Give it to someone you love and trust (I wish my grandfather would have ) See if this can help you find peace in the dreams about unfinished business. Then see if you still dream that you will die. If you do try this, please let me know if you still have the dreams. Especially the car crash...