Is the middle still sound or is that soft and mushy, if so it wont grow back. But you can clean it up by taking all the dead stuff off and then keeping it on the dry side until you can plant it out. Hope this helps.

you say it has gone rotten, what part of it, and where is it planted. If it is the base, I would check to see if the ground is waterlogged around it, and move it if possible, if its the top section it could be that snow and ice have taken there toll over the winter, clean up the top by removing the dead leaves and check to see if the crown is firm, if so it should by rights return..

These are not hardy in certain parts of the country..so it will depend on where you live and was it protected?