It won't have appreciated being inside at all. Now that the worst of the winter is past, suggest you start hardening it off ready to put back outside in ten days or so. Give it a general purpose feed, or repot if necessary, when you do leave it outside again, prune any bits you think might have died off, and hopefully it will start to grow again.

My daughter took hers inside and it died - too warm, too dry and above all, not enough light. I think (she disagrees) that it was in too small a pot, too. We have an olive tree growing outside, and we don't protect it in winter. Everyone on this site will tell you that we have some pretty fearsome winters out here (I moan enough about them) and as long as the weight of snow doesn't break branches, and the tree itself is well established and planted in the ground, it can survive really low temperatures (-22°c here for a few days). The real killer is getting the roots frozen, so anything in a pot should be protected.
I suggest you do everything that Bamboo has said, and keep your fingers crossed as well. I do hope it springs back to life. Welcome to GoY, by the way.

Thank you both for your replies.