I was using thunderbird v15.0 on ubuntu 12.04 LTS till now, and have the lightning extension installed to manage calendar within thunderbird application. everything was working fine until i decided to update thunderbird to the latest version 16.0 from ubuntu repository. installation was successful, and the profile everything was taken care of perfectly, except that now lightning is not working - it is disabled as lightning v1.7 is NOT compatible with latest thunderbird v16 yet. As a result i am at loss with all my scheduling. now, i would like to go back to thunderbird v15 so that i can use lightning. ubuntu repository only gives TB v16 now. on mozilla site, they are still giving v15 for linux, so i downloaded the tarball and uncompressed using command line. now i have a folder called thunderbird. there are no readme/ configuration files. there are following 'executable files' inside this folder: crashreporter, mozilla-remote-client, plugin-container, thunderbird and thunderbird-bin. i tried invoking thunderbird and thunderbird-bin from command line using sudo, still nothing is opening up. i have execute permissions for this folder contents. i m quite new to linux. please let me know why i m not able to launch thunderbird. did i install it incorrectly? please let me know if i can get a .deb package for TB v15.