It should recover again when the tempt goes up again come spring time. Don't lose your cool. Meyer is the most temperamental citrus overall.

Second Bencelest's comment - I've lost count of all the times I've annoyed my Meyer lemon and it's defoliated. Somehow, it's still alive, after about 20 years with me.

i have a similar problem i bought a meyer in the summer and it was doing very well in the conservetory however come winter when the temperature in the conservetory droped to aprow 5'C I decided to place it in the window of the spare room.
since then it has lost all of its leaves however it is still holding its fruit?
i heard somewhere about a condition called winter leaf drop does anybody think this could be the problem and if so should it come back to life come spring?

I am really surprised that so many seem to be saying that Meyer's is a difficult citrus. My experience couldn't be more different. Mine has been overwintering in a cold garage where the January temps ran from 32 F. to 55 F., it was hardly watered and the light is decent but not intense. It is literally covered with fruit now and is beginning to push active growth in response to stronger sun and longer days. It also blooms throughout the year. Meantime, another Meyer's I brought inside for the winter, is covered with scale. I intend to wash it thoroughly and get it out of the house A.S.A.P.. So far, I would say I have been least impressed with flowering and fruiting (or lack of) of true lemons (not the hybrids). Maybe after a good year, I'll feel differently. Yes, citrus are good about recouping from defoliation. My Persian lime recouped nicely in the basement (under fluorescent) after some problems in late fall--currently in flower actually. Good luck!

This is my first attempt with the Meyers Lemon Tree; I did everything that it told me to do when I received it, soil, compost, mulch, fertilize, etc.. and it was doing fine. Then something started eating the leaves so I asked the garden store what to do and they sold me a bug spray for that particular tree(I believe mostly boiled onion water as that's what it smelled like) a week later the leaves started falling off. Is it gone or will the leaves come back? I also have a Meyers Lime tree that wast attacked by the bugs and it's doing great so far( even has tiny fruit)

HU, I strongly doubt that the spray you used was boiled onion water. Whatever, all you need to control the big 5 citrus insects (mealybug, aphids, scale, thrips, mites) is a horticultural oil. It kills all five, totally non toxic to man and animals, even can be used in organic culture. Insects NEVER EVER become immune to horticultural oils. Lastly, horticulture oils never damages plants when used according to the label.

Meyers are fairly cold tolerant (@subtropix). They are also really sensitive to changes in lighting, so moving them indoors (or outdoors) without conditioning them can cause leaf drop.