I am so sad and I don't know how I can move on. What can I do to not think about it?

I was at the funeral home and I saw my friend and he was dead. I was very sad that I started to cry. This was my first time seeing a dead body in real life. Its very sad,depressing and tragic death for him. I'll never forget him. He was a good friend and he was like my best friend. He was only 17 years old when he died. He suffered from brain damaged and he was in a coma for 50 percent living and 50 percent dieing. He died on April 8 2011. I've known him since the 9th grade in 2009. I will never find a good friend like Daniel. Its going to be really hard. I'm trying really hard to move on but its going to take a long, long time. My dad told me that there's nothing I can do about it. Its just so hard. :'(