Sometimes when you edit the .htaccess file in cPanel, the lines must wrap and this causes a line break.
The line break is a common reason for site errors.
To fix this, open a text editor (like Notepad) and paste your .htaccess code in.
Be sure that Word Wrap is off (under Format).
Save the file as htaccess.txt
Upload this new file to the proper directory.
Rename the current .htaccess to htaccess-old.txt
Rename htaccess.txt to .htaccess
To avoid further problems, don't open this .htaccess in cPanel anymore.