There is a Map feature that has existed since LAST February called 'show active quests'.
It can and will show you in just one single mouse click which square it is in. Or a few clicks if it happens to be in a sub map (the quest name will be colored red until you are in the correct map and then it will be colored green).

No not a holiday area it gets relocated but should be instantly found using the 'show active quests' feature.
And the fairgrounds itself is always available but should show up using the 'show active quests' feature.
If the name of that quest is colored Red, then go to one after the other of all 8 of the small maps.
Scientists Castle, Underwater, Far Away Lands, Underground Pyramid, Center of the Earth, Wonderland, Pirate Island and Haven Crypts. There are some other areas on the main map that are not actually mapped, zoo, haven castle, 4 areas related to the kings quest in the Mountains, Haunted Forest and Lost City, and an area between the Desert and the Jungle. If the quest is colored red on all 9 maps then check all these other unmapped areas. But the giant or the chest can actually only appear in a few of those.

Lastly, it will not show a ? anywhere on any map unless the quest s actually complete, what does your quest log state? But the 'show active quests' feature should SHOW what square it is located in whether or not it is completed.

it says it is complete and it has been weeks since I "lost" the treasure chest. guess I will have to go to the far away areas one by one and check all of their maps. ty for your help

ok will try again ty for your help Raymond

Please verify exactly what it says.
Does it say something like 8/8 helps obtained...?
Or is it in the Completed Quest Log like I mentioned above.
If it's 8/8 then perhaps the current bug of the maps not having ?'s on it is preventing you from seeing it. But the "Show Active Quests" feature should still show exactly where it is, it will be green on one of the Maps and Red on every other one, unless it's in one of the unmapped areas. But have you been into any of those areas recently? If not then there is no way it would have spawned in any of them.
If it's in the Completed Quests Log, then look all you want, IT IS NOT CURRENTLY IN OPERATION and you are just going to have to wait for it to spawn somewhere.

I do understand what you are saying. it is in the current quests and says return to treasure chest. is ok I will take some time to check the maps by hovering my mouse over the squares and check other areas soon. i do thank you for your help Raymond

I had not considered that since the Developers made it 'automatic' that Giants and Chests that occurred in transitory Holiday Event squares would move to the very first actual square in the game when those transitory squares no longer exist. They started that at Halloween and repeated it at Christmas.
http://forum.djartsgames.ca/?thread_id=676
http://forum.djartsgames.ca/?thread_id=695
I can't find the actual post with the conversation I remember so clearly.
Mr. X on day 1 of Halloween: What would happen if I get a Wealth Chest or Giant in a Halloween square and not complete those before the end of the holiday?
Justin a Developer: Well we have 2 weeks to figure out what we will do in that case.
Me: That's good to know.

I had forgotten that there was an error when they reimplemented that for Christmas. But that's not hard to understand, there are many other errors (right now) in the game. Like the 3 final 'solved' positions of the 15 square puzzle that are in no way solved but the game thinks it is and strangely only when the 'hole' moves in one particular direction. Or the fact that many of us are more than 100% done in the game, I'm 102%. Or that the game thinks I have 520 Customization Items, but I only have 504.