You cannot get back there without console commands. The console command you are looking for is "coc " and you'll probably need to do it again to get out.
Use coc skuldafn02
to get there. The codes for Skuldafn are skuldafn01
trough skuldafn04
. 02 should put your back in the Skuldafn temple. coc whiterun
might bring you back home. Not sure about the last one.
When your follower "dies", they enter a pre-death state that generally allows them to come back to full health immediately after battle. However, if they continue to take more damage after entering that state, they will die permanently.
If there's a chance your follower is still alive but nowhere to be seen (for example, if they entered the pre-death state and you ran off, thinking they were dead dead), fast traveling to a location should cause the follower to appear back at your side.
If fast traveling still doesn't produce your follower, they're almost certainly fully dead. You can confirm this by trying to pick up another follower: if they agree to come with you, the other follower has ceased to be. Sorry about that.
The only thing you can do at this point—if you're not keen on loading up an earlier save or using console commands—is to find where your follower died and loot their corpse.
If you are amenable to using the console, generally you still need to find where your follower died to ressurrect them: when you do, open the console, target their corpse, and type:
resurrect 1
and press enter.
However, you can get around even this restriction by selecting the follower by using the prid
command anywhere:
prid <RefId>
Where <RefId>
is the ID corresponding to the follower, found by using the Creation Kit or by looking up the follower on UESP. Once the follower's selected, use the resurrect
command mentioned above.
Best Answer
According to The Elder Scrolls Wiki there are 3 ways of doing it: