?

He wasn't born a vampire, so there was no way he could live for a thousand years. Think he just got old.

He could cause he had Yukis pure blood, but i think he died to wake up Kaname along with Yuki tho im not sure.

Level-D vampire lifespan is short from the start. Zero can life through 1000 years is long enough, it is because he consumed pure blood and his hunter blood

It was Yuki who died to wake up Kaname, Zero was already dead by then.

I think so too but it's not too clear with the last chapter of them..I think Zero also sacrificed for Kaname weren't they both there when they were telling their goodbyes and they ll make him human after a 1000 years or something?

Really? It didnt seem that way. That doesnt make sense.

Zero, being a Level E, even with Yuuki's pure blood wouldn't have lived long. Plus, the ritual to make a vampire human would be only able to be performed by a pureblood because of their great powers. If we look at what happened to Juuri, her mother, she sacrificed her life to make Yuuki human for a time. Juuri's husband Haruka was already dying from being stabbed with a hunter weapon so did not contribute to the ritual, thus meaning it is performed by 1 pureblood. Perhaps Zero died and then Yuuki felt she didn't want to live any longer without him or Kaname so she decided that she would perform the ritual on Kaname. I hope my reasoning makes sense but Zero couldn't have contributed to the ritual as it only required 1 pureblood = Yuuki. And as he wasn't there when Kaname woke up then it would be assumed he was dead.