So, through dragon attacks (Faendal in Riverwood) and Vampiare attacks (Adrianne Avenecci in Whiterun), I am missing some NPCs I would like to have back in the game. I happened to notice both were killed right after their respective demises, and resurrected them, though clearly the game recognized they were dead, since the Jarl sent me a letter or condolence.

They were around, until the next time I logged in and loaded a saved game. I'd like to get them back. I can look up their IDs, obviously, but are there a commands to deflag them as dead and replace them in game. Adrianne, in particular, I would like to have because I HATE losing vendors.

The reason they vanished is because they have a script attached to them (WIDeadBodyCleanupScript) which runs immediately after they die. It waits for a bit, and then disables their (now ex) corpse and enables a burial urn in their respective city's Hall of the Dead containing their personal effects.

If you want them back, try using PlaceAtMe (MyID). If you don't mind them returning to life post-cremation.

There isn't really a good way to reset that script in the console, though.

Assuming you already did the resurrect command from what I read, did you try this?:

http://www.uesp.net/wiki/Skyrim:Console

Not sure if that will do it but from reading it, it sounds like it unless I am misinterpreting it.

Thomas Kaira's post pretty much answer's your question, as well.