I dropped the quest when I was leveling and said I’d eventually go back to complete. But its no where to be found and I can’t find, plz help
Best bet is to use site like WoWhead and retrace your steps.
https://www.wowhead.com/classic/quest=26/a-lesson-to-learn
It’s 4 part quest so you look thro all those associated quests in order to figure out where you left off. On the right side of that website is the quest chain list 
Go to each quest giver which you can see from the right side again, with a huge !-sign and a name.
EDIT: I just realized they added the scripts. Scroll down to the page to find similar to this:
See if you’ve already completed this by typing:
/run print(C_QuestLog.IsQuestFlaggedCompleted(29)) if you wanna avoid running around ingame.