c:\Users\<USERID>\Application Data\Thunderbird\ProfilesWhere <USERID> is your userid. Then look for the folder called <Random Junk>.default -- that's where your precious mail is stored.
Computer Tips - Thunderbird: Where is my mail files
Date: 2008nov10
Update: 2015aug18
Product: Thunderbird
Q. Thunderbird: Where is my mail files
A. On Windows its in:
Look in...