This is interesting, since it seems my quest marker actually led him right to him. Unless the quest failed and/or it was a glitch that it did that, you should not have much of an issue following it that way.
Lod died on me not from a dragon attack but a Vampire attack. I recieved the quest before he died and was still able to complete reuniting Barbus w/ Clavacius Vile
If a specific character that you need around has died, simply use player.placeatme and their ID to spawn them back in the game.
Unless your on a console then you have to reload before it happened (if you can) and save them. Don't use placeatme though as that makes a copy that doesn't always work right for quests use (for Lod) -
prid 0003A19F
moveto player
to bring his body back if its gone and then (he should still be targeted if not click on him with the console open) -
recycleactor
I cant load before he died because I tried it and he died before I got to falkreath