I need some advice! My crush is driving me crazy!?

Okay so im going to explain this the best that I can. So i have a neighbor who i have known since i was 9 and im now 17 on Thursday! :p okay so we were best friends and we kissed! So we have made up a couple of times and it just hasnt worked out too well. So just about a month ago he messaged me on Facebook out of no where (i like him so i was super excited) and he wanted to ride bikes like we used to do every night! So we rode bikes 3 different times and i thought all was going well and we were friends again and we were gonna work on this. But then out of no where he just started ignoring me. I didnt do anything at all.. And he had his keychain at my house and i found it and so i told him and he asked me if i could put it in him mailbox! Well when i got back inside i told him i put it in there. And he messaged me back and told me thanks and he couldnt ride bikes that night. So i told him to just message me when he could and its been 2 or 3 weeks and he still hasnt messaged me. So ive been going to his youth group that my friend who also goes there invited me to! And ive been 3 times and each time hes only spoken to me once! Hes either says hey or bye. Thats all and when we are alone together im like a complete stranger. I just dont understand whats going on..He was just talking to me a couple weeks ago and out of no where hes now ignoring me.. and i know i can say something but im very shy and just dont know what to say!! Im pretty dissapointed and very sad about this actually. Especially since i like him!! But idk if i should try to talk to him about this or just leave it alone and stuff. Its hard when i have to see him when he goes down the road and at youth group and bible study. So if anyone has any advice on this PLEASE help me im begging you!! Im tired of having to go through this everyday!

P.S. any suggestions on talking to him or what i should say to him! whether its me asking about what our friendship is or just regular talking if I should even talk to him at all!

Thanks, Candice.