Hello Amy - Sending me a couple digital photos would help, but
here are the basics....
You can scrape off the outer bark on a few of a
tree's branches (using a knife or your thumbnail) to see if there is still some "green" tissue
just beneath the bark. Bending and "snapping" a few twigs will
also give you an idea if they are flexible and still alive, or
brittle and dry. Those are my
two twig tests for you to
use.

Assuming the twig tests indicate there is still some life left
in your tree (by the way, the name Arborvitae means "tree of life") you may want to shear it back lightly to "reduce the load"
on the root system. Trimming it back will get rid of some of the
excess branches and allow for some of the buds lower on the
branches to leaf out and grow. It will also help remove some of
the brown needles.
Needless to say, if the soil around the tree is dry, start
watering it once a week. You might also try an application of
MIRACID (the 'cousin' of MIRACLE GRO) which you mix with water
and pour around the root zone, according to the label
instructions. Try one application of Miracid now, and two more
applications at one month intervals.
You shouldn't have to wait very long before you know the final
verdict, since your spring is probably a couple weeks ahead of
ours. By June you should know whether the tree has made it or
not. Hopefully it will look as green as the Arborvitae on the
left.
I'll be interested to hear back from you on your final outcome
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