I can't see my .htaccess file under cPanel's File manager

.htaccess is considered a hidden file in linux.

Before entering your file manager, cPanel pops up a message asking you where you would like to go within  your file structure. At the bottom of the radio buttons, you will see a checkbox asking you if you'd like to view hidden files. Check that box before entering your file manager and you will see the .htaccess file.