. (dot) files are hidden by default on Unix/Linux systems. Most likely, if you know they are .htaccess files, then they are probably in the root folder for the website. If you are using a command line (terminal) to access, then they will only show up if you use:
If you are using a GUI application, look for a setting to “show hidden files” or something similar. If you still have no luck, and you are on a terminal, you can execute these commands to search the whole system (may take some time):
find . -name “.htaccess”
This will list out any files it finds with that name.