I told Esbern and Delphine to meet me at Karthspire, I did some questing along the way and when I reached the camp, there were a bunch of forsworns and a dragon joined in the battle however my partners were nowhere to be found. I cleared out the whole camp from the forsworns and the dragon with a bit of strategy and my level 33 Nord. Once I went inside, the game got considerably slow sporadically lagging, I didn't pay much attenton and figured out the puzzles without my partners advice because they weren't there. At the Sky Haven Temple's entrance I was stuck and couldn't do anything except seeing that the quest marker was placed on the big face. I thought that my partners were probably running slow or walking so I decided to wait, except instead of waiting I went questing. After several quest, dungeons, and getting to level 37, I went back to find Esbern standing looking at the statue face, he told me how to open it and I did. Everything was normal until he lit up the torch by Alduin's Wall. Esbern stood there not saying a thing so I tried waiting and questing to see if he would eventually move... nothing. So then I noticed the other torch and knew Delphine was the missing piece of the puzzle. Searching online for where could Delphine have gone to, most answers said that some kind of bug made her dissappear and that it was a game ending bug. So I have Delphine dissappear, while Esbern is there staring at Alduin's Wall, with the dialogue: "Isn't it amazing?" making the quest uncompletable.

I have this quest bugged as well. and according to the unofficial Skyrim patch website (Who works with Bathesda to report bugs to them), Bathesda has no plans to pursue the fixing of this bug. Which is ridiculous, because it breaks the main quest line rendering the game unfinishable. Yet Bathesda can fix all of these side quests and optional stuff which doesn't really help people screwed over by the main quests.

How about a link???

In my experience if you have followers in a specific quest(s) don't let them go out on their own. More often then not they end up lost somewhere in limbo with no return. Also if you have followers that follow you, fast travel to a point near your objective.

Another tip is saving before you enter a major quest and keeping that save until you complete it. That way if it al goes horribly wrong you still can revert back to the point before you took the quest.

^{ANy good TES player should know by now that saving before any mayor and known quest that has been openly reported to be glitched is a "must" yes there is a big gitch with this quest that has not been fixed yet if you did not have that save file that takes yoy back u will have to wait for a patch....and FYI......NEVER continue the game when you found a bug.....that means that from your level 33 to level 37 all your saves files included the bugged quest .......thats bad....}

Another good tip is to not do other quests in the middle of your current quest, especially when it involves followers.

very true ......try always to keep one quest line untill the end....and avoid crossing quest lines..like the civil war and the main quest ..it gets so screwed up when you get to season undeing if you have civil war quests open....here is the order i did my las play through and i had 0 bugs "nada"

1- college of winterhold (im a mage....always will be)
2-thieves guild
3-dark brotherhood
4- bards college
5-companions
6-main quest
7-Civil war

NOte that when i finished a quest line i would just wonder for a while and do quests like the daedric artifacts or word of power locations...