If you installed Bancha Bash, you can write the following line on your unix shell:
If you don’t have Bancha Bash, download Bancha from the official GitHub repository https://github.com/squallstar/bancha and unzip it into the root of your virtualhost. Normally the index.php file will be at your root.
The base structure is composed as follows:
.htaccess application/ attach/ core/ themes/ index.php
For the best security, both the core and the application folders should be placed above web root so that they are not directly accessible via a browser. By default, .htaccess files are included in each folder to help prevent direct access. If you move, the above two folders, be sure to update their paths on the index.php file ($user_path and $core_folder variables)
When you’re ready, go to the next chapter: Understanding Bancha
You could also read how to upgrade an existing installation: Upgrading From a Previous Version
To reinstall Bancha, remove the is_installed row from the settings table of the database. Then, skip to step 3 of the above installation process.