Hmm...Elhan should be right where you left him. As IrishHound said, when you give it to him, you get a media cut scene..I have no idea what might be wrong for you, sorry. Best bet is to just reload if possible.
Those ways into the Elven City won't help at all if you didn't get into it to begin with, I don't think.
slight spoiler, but they asked for it:
waverider- the lanthorn is in Bodhi's coffin/boat thing when you finally stake hwer in the lowest tombe level in graveyard district.
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Playing the cutest li'l Chaotic characters since 1996.