If it’s Apache server, you need to have a writable htaccess file. Usually it’s writable but if in case it’s not writable then give it write permission using your favorite FTP application (like Filezilla, CuteFTP, etc.) or hosting control panel.
In case of FTP:
- Go to WordPress path in your FTP program (WP usually is in public_html, htdocs or www folder)
- You see .htaccess in your WordPress root directory. If you don’t, make sure your FTP program can display hidden files
- Right click on the file. Choose Permission or Properties and change permission to 777
- After configuring Hide My WP you may return htaccess permission back to 655
You can find the video tutorial here.