Does all mail eventually get to it's destination? Or is it thrown away if the address is wrong?

I have been waiting to get two pictures from my school that were said to be sent to everyone over the summer. All my friends say they got theirs already but i never got mine. Summer is almost over so I know it should have at least come by now. Is it possible it will be thrown away since to never got to me? My address was changed over the summer after the pictures were sent out too.

If the mail for you is sent to an address you are no longer at, and there is no forwarding address on file with the post office, it will be returned to the sender. I would go back to the sender to verify they did not get it back. If it went out without a return address (unlikely), it would go into dead mail. The post office holds the mail for a period of time to see if it is claimed by someone. You might check with the post office outlet that serviced your last address to see if they are holding it. On rare occasions (relative to the number of pieces of mail handled) mail is lost or accidentally destroyed, in which case you are out of of luck.
Can't the sender make you new prints of the photos?