Is the whole tree brown and pine needles falling off? Also how big is the pot? Larger the tree the more roots it has and water it will need.

The quick answer is that it sounds as though it's dying. The needles won't grow back, I'm afraid.

Most pines or other needle conifers won't re-sprout once the needles are dead, though a few can sprout again on younger twigs. If there is moist green under the bark of those twigs, I would give it a few more weeks, just in case, but the prognosis isn't good.