If your tree is dried out and brittle, sorry to say it is most likely dead. There are some small trees sold at Christmas time( Stone pine) that are really just for decorative purposes. They have soft needles and a bluish cast. Unfortunately, they are not hardy in colder regions and usually dry out indoors over the winter. Christmas tree can be kept indoors for a short amount of time but then needs to be planted outdoors. If it shows any signs of life (new buds at the tips) repot it in fresh soil (check the roots and trim off any decaying dead material) ,then place the pot outdoors in a shaded area. Even after all that effort your tree will be scrawny and mishappen tree once all the dried needles fall off.