I was just wandering around and came across what I thought was some kind of bandit outpost being attacked by a giant. Random encounters like this tend to happen, so I didn't think anything of it. Several "bandits" were killed and a mage was in a tower launching ice spikes at the giant. I let the mage do most of the damage and shot a few arrows into the giant. I looted him and killed the mage with bow shots. I was told I failed "The Cursed Tribe."

I was unconcerned, thinking it merely some meaningless quest, given the small area involved... so I ventured into the encampment (had to jump the wall because the gate was locked). I roamed into a hall of some sort and was set upon by more "bandits" - which were actually orcs. Since I already failed, I thought I'd just dispatch them and loot... but the final guy was heavily armored and very angry. I had him down but then he miraculously healed back to full. WTF? I ran inside again and hid (got some nice loot, though, so score!) but he came back. Luckily, I could stealth him. Backstab did very little (is that armor made of adamantium?!?)... but my companion finally showed up. She died helping me kill him (poor Illia)... and he only went down to one knee before fully healthing back up. Lamesauce. I knew I had an immortal NPC on my hands, so I hightailed it and eventually got away.

Now that the story has been told - is there any way I can get that quest back? Will it reset at some point, with the orc chief stricken with amnesia over my attack? Or is it just a quest I can never complete now?

Thanks in advance for any help!

No, that's that. You needed the mage to start the quest.

Ah well. Not germane to the overall game, so I guess it's not that big of a deal to have missed out on it. I came here because the Skyrim wiki had no info about the quest respawning... and found out the reward is a weapon I won't even use, so it's no huge loss.