I'm playing Skyrim. My directx version is 6.14.10.7008.

The quest Repairing the Phial won't start. I've already completed 'the White Phial' by delivering the damaged Phial to Nureline. Now I've gained full access to the Throat of the World and progressed through the main quest 'Season's Unending' already. (Which is far beyond the point where I should've been able to start the quest.) I've even fought an epic battle there.

I've been waiting for the letter to arrive, to start the quest, but none came. My level is 69 at the moment, so I don't think my level is a problem. I've checked with many places, and found that many players have the same problem. They can't get the quest to start even if all the requirements are met. The last playthrough, this quest started without problem for me, so I think this is definitely a bug. How do I fix this?

At this point, I accept suggestions on using console commands. (But Christ, I hate it. Bethesda, is there a playthrough that ISN'T glitched?) I've tried 'setstage ms12b 10' but it won't work. What parameters have I missed?

C'mon! Someone gotta know this!

I'd have double check...
But your Alchemy is at high level? (or that was Conj for nother one..)
Few fixes come to mind...

-You can also try waiting near gate (I use Whiterun since you can see pretty far out) and use wait command for 3-6 hours at a time. (i'd say.. 3-4 days tops)
Incase the Coiuer is traveling to you.

-You can also try inside towns (at gate) and use wait command.

-Or, (Waiting works for me) You can go to each Town and check to see if Courier is there. I have found Courier just sitting there...doing nothing. And when you talk to them they hand you several letters. (Heck.. one courier was naked.. )

-Last one is to Complete a Word wall quest, then ether use Thum in a location (to get the letter for next word wall) or Talk to Greybeard and get location, then finish it. (Don't forget to use a shout) so you'll recive a letter form Courier who will often update.

That how i've gotten it to kick start.

Does Alchemy really have something to do with this? I'm not the one repairing the Phial, but oh, well. Nothing to lose anyway. I'll try it out and report back.

I don't think it did... Like i mention.. that might be Conj related to some other quest. (and not alchmey)

I've tried all suggestions except the Word Wall. I've already hunted down every possible Words except ones in Skuldafn and Korvanjund, which are quest-locked.