This is the second time that I've frozen my garden to protect my Superfood as my garden is so quiet, I prefer to keep it frozen while I'm away from computer, whether sleeping or not, and I come back and the garden is unfrozen and naturally nearly all my critters have been missed.
I KNOW it was frozen, I checked it and had a friend in another garden check it for me. My Facebook was not hacked, no-one else plays my game. Why does Fairyland do this? Is there some rule that you can not freeze your garden when there is a plate of food?

How are you accessing your garden when you come back? If it's via a bookmark or saved link, rather than the My Garden link on the green toolbar, you may be using a link that has the unfreeze command in it and thus unfreezing as you open the garden. Check the URL you are using if so, it may have an "action=unfreeze" command on the end which is causing this. Use a clean link or the My Garden link instead if so.

If using an 'unfreeze' link to get back to the garden, it would have unfrozen at that moment and not have hours of missed wildlife.
There are so many posts like this that I'm starting to wonder if there really is a problem.

That's true, but it's also possible she is using the link earlier and thus unfreezing it accidentally. If there is a genuine problem, it will help to check the URL etc first to rule out common causes of this issue before reporting it.

Something else which can cause the garden to unfreeze is if you use the Back button to exit your garden immediately after you freeze it - it undoes the last action so would unfreeze your garden.

Tracy that is Incorrect ~~~~ when you freeze it in the address above it says  action=freeze when you hit the BACK BAR it does NOT UN DUE it, it shows you  Garden frozen.. Try it in your own garden but it does NOT unfreeze it

It depends on the browser, from what I've seen.  Mine does, maybe others don't - hence I said it CAN cause the garden to unfreeze, not that it DOES cause the garden to unfreeze.

It's worth a check because I know (from experience!) that it can cause the problem which the OP was having.

Thanks for replying. I froze the garden, clicked on a plant to check it was frozen. and closed my garden by using the X in the top right hand corner. I did not access it from any other computer until going online again in the morning where I went to Facebook and from there to Fairyland. I did absolutely nothing odd.
I have heard from a few people who have said the same thing has happened to them.

Glad I'm not the only one. Just found my garden active when I know it was frozen last night. I always check too and like Shaddles I remove the game before logging off at night!!

The other action which can cause a garden to unfreeze is if you accept a gift - even if you think will just go to the pending area - it will unfreeze your garden - learned that the hard way with the holiday calendar.....