Nirgon
Log Wizard
First one was the water temple in Ocarina if Time. I took a wrong turn or missed a key, and lowered the water level. Couldnt go forward or back. Had to make a new start on that one.
Second was also from Zelda. I was at the end of Wind Waker and was just finishing all the side quests before I went to the final dungeon. My brother sold his gamecube with all the games without telling me. Only recently made a concentrated effort to beat it. Definitely worth it.
Ok I had this happen too and was ASSURED it was impossible to get stuck.