Try to get proof that the shares were sent to unclaimed funds and then contact the Comptroller's Office.
The above answer, and any follow up comments or emails is for informational purposes only and not meant as legal advice.
It may be in the process of being escheated but not yet considered as such. You likely want to get an attorney in Boston (where ComputerShare is) and file a turnover action before the stock actually escheats.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.