Hmm.. i thought not. But now i looked in the quest.log. and there is an active lvl. 3 quest. About 60 - 70 seasons ago I walked with a champ. on an ancient ruin. Tryed to pick up the quest. Did not know that i have to fight immediatly. My champ. was not good, so i leave the ruin with out a fight. I thought that "finished" the quest. Hmm... what now? How can i finish the quest?

Currently, if you choose not to fight the monster/spider/bandits/etc. the quest location disappears from the map, and you then have no way to complete it.  This is a known issue, and hopefully it will be fixed in an upcoming patch.

My recommendation is to always save before moving on to a goodie hut, so that if you end up choosing 'no', you can just revert to your savegame and the quest is still there for later.  A pain, I know, but that's the option for now...

Actually, those level 3 quests are available in a quite a few locations. If you retreat from one, it disappears, but look long enough and you will find it again. Meanwhile, you can't explore other level 3 quests. I had that problem in my last game, with the Uber good armor quest. Retreated first time and lost sight of the quest. About 30 turns later, I found it again....and had to retreat again. Grrrr! So I put together a good army and went looking for it next time. Just found and fought the quest successfully and the other level 3 quests opened up again. Just be patient.