I have been unable to use quest helper for the past day or so. I log off and log back in and it still will not appear. Yes, I am trying on quests that use it. :)
You can turn Quest Helper on and off by pressing the letter "T" on your keyboard. As QTNikie said, it sometimes turns itself off for no apparent reason, or it may happen if you accidentally press "T" while pressing other keys.
If pressing "T" doesn't solve the problem, you may want to contact Support.
it used to drive me nuts and i found out what was happening most of the time it happens after boss battle or i will accidentaly forget to push enter before i start typing lol. glad you got it figured out. im jealous of you tho, you can play. i have been off the game stuck on patching for 7 or 8 days now my husband too.