Oh dear, it looks a bit dead. Scrape away a little of the bark from the main trunk with a fingernail. If the wood below is green then it should re-sprout, if brown then it may be dead. Leave it until end of May before chucking it on the bonfire. Sorry.

is it in a pot? if so maybe the frost got to the roots and killed them, as Volunteer saysgive it a bit longer just in case the roots have survived -- it will need time to re-grpw