Login into your CPanel
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Often you can access your CPanel just by adding /cpanel to your domain name ... example.com/cpanel
Access the File Manager
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Although your screen may not look 100% identical to the one above, every version of Cpanel does come with a "File Manger" option somewhere.
Choose to Go to the Webroot
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Find htaccess.txt
Your files and folders will be listed alphabetically. Scroll down until you find htaccess.txt
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Check the box next to htaccess.txt and click "Rename" at the top of the page.
Change the file name to .htaccess
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Enter .htaccess as the new file name and click "Rename File"