There are many ways to update a WordPress theme, from the one-click update feature built into the WordPress dashboard to the slightly more complex manual update. There is no more important advice than this when updating your theme – always backup your site, complete with database before you do anything. This is an important fail-safe and a lesson that users usually had to learn the hard way.
If you’ve customized your theme and did not use a child theme to make the changes, you’ll want to download your stylesheet (usually named style.css) in order to preserve your changes after the update. The manual update process will overwrite all of your theme files, so it’s important to have this one stored on your hard drive to upload after the theme update.
First, access your cPanel or your hosting account’s file manager via direct access (usually something like http://www.yourdomain.com:2082 or http://www.yourhostingcompany.com and click a login link from there) or via FTP, which is generally done through ftp://www.yoursite.com, or an FTP client. Either way, you’ll need your login credentials to access these areas.
Once you’ve accessed your file management system, you’ll navigate to your
wp-content/themes folder and upload the updated zip file containing your theme.
If you’re asked to overwrite an existing file, click yes (again, making sure that you’ve backed up your existing WordPress installation). Once the file has uploaded, return to your theme’s directory and you’ll see the zipped file.
Highlight that file and choose “extract” or “decompress” from your file options menu. You’ll see a popup that indicates that your files are decompressing and you may again be asked about overwriting existing files, depending on your host.
If you’re updating via FTP, simply download the updated zip file of your theme to your hard drive. Extract the files, and then upload to your server in the existing theme folder. That’s all – have fun - happy editing!