I was doing a radiant quest for the companions and they told me to rescue Amren in Redoran's retreat and it seems it's impossible to find him, i kill all bandits and Amren is not in this dungeon.

Even the map/compass's cursor seems to bug, not the same indication on both (map's cursor show me a place near from a place of Giants/Mammoths and nothing here too and the compass's cursor shows me Whiterun and when i go to Whiterun, its show me somewhere in Whiterun but an unreachable place without exit Whiterun...)

Nothing in Whiterun, i searched in every place, in his home, in the market... no Amren.

I waiting several hours, something like 2/3 days...

So what can i do now? Companions are [censored] off in my game? Please help me.

Firstly, check the Hall of the Dead to see if there's a coffin belonging to Amren there, which indicates that he died.

If you've already completed the questline, you can kill your current questgiver to fail the quest and remove it from the log. Otherwise, you'll have to reload.

Or, you could be missing something. Try turning on floating markers.