Is part of the shaft still in the bottom of the putter? if so I suggest you take it to your local pro or find a clubmaker, because it can be a problem to get the rest of it out, if there's not then the shaft has just come out of the head, you can remove any residue of the old glue, clean up the shaft and re-glue it yourself.
You can buy the shaft glue on resellers sites who sell club fitting accessories. Its not difficult to replace a golf shaft, just make sure you align the grip and the shaft if fully engaged in the head before the glue sets.
Check out the videos on YouTube showing you how to do this!

Is the head or neck broken as well? The photo seems to indicate that it's a shaft break and a new one could be installed.

Epoxy. Takes about 30 seconds to reglue and a couple hours to set.

that isn't broken, it's just separated.

take it to a shop and have them epoxy the shaft back into the head.

Simply clean out the epoxy residue from inside the hosel and re-epoxy.. Make sure the grip is lined up!

Thanks everyone!! I epoxy it back together! Maybe it will knock off a few 3 putts this season!

Very nice
I was cringing when I saw the thread title, but felt much better after I saw the pix.