.....Now my quest runs into a dead-end (no pun intended ....much!) at a pile of ashes, at the College of Winterhold. The quest is still live and has not failed but it was an early quest and I have put in well over 150 hours since I last tried to find the quest character and now I am tidying up my unfinished quests, I'd like to sort this out, even if the quest fails.

Any ideas?

What quest is it?

Reload a save prior to the dragon attack. Hopefully this npc survives the second time.

If you're on PC, I recommend a neat little mod called Run For Your Lives. Makes npcs run and hide when dragons attacks.

He said its an early quest, so the character probably died some time ago i suppose?

If so, you could attempt to advance the quest stage to bypass the NPC, or try resurrecting the NPC? Though if i remember correctly resurrecting NPCs usually doesnt work. So you could try bypassing the quest stage instead. Can be found on the wiki. If you're not on PC then there's nothing for it.

You're dragonboned. Once an NPC is dead, and part of a quest, that's the end of the quest, which remains open in your journal until you finish the game.

As others have said, you can reload from a save in which the character is still alive, but personally, I'd forget it and move on. Not like there aren't 10,000 other quests you can do instead.

I took it to mean he started the quest early but the npc got killed by a dragon now. But it's of course possible it happened a while ago, and it that case, I would just have moved on. Unless there's a workaround for that quest stage, but that depends entirely on what quest it is of course.

Isn't there a resurrect console command? That should work on PC but if you're a console player than you have to just load back. This happened to me on console once, a 'challenger' approached me and asked me to duel, but before I finished him a dragon flew in and carried him off. I still have the quest marker in miscellaneous quests...