There are many reasons, so start by doing one step every time and try to access your website again and see if it fixed:

1. Disable all extensions you have.
2. Clear/Flush your DNS Cache: https://www.pcmag.com/how-to/how-to-flush-your-dns-cache
3. Clear Firefox cache data: https://support.mozilla.org/en-US/kb/how-clear-firefox-cache
4. Clear Firefox cookies: https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox First try to clear cookies for your website, if didn't work, then clear all cookies of the browser.

Thanks for your prompt response

- I found it too technical for me so I will show it to a person who has the technical skills necessary to follow your suggests.

All the best.

This issue can be caused by corrupted cookies or blocked cookies.

• check the permissions for the domain in the currently selected tab in "Tools -> Page Info -> Permissions"

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Settings).

"Remove the Cookies" for websites that cause problems:

• Settings -> Privacy & Security
  Cookies and Site Data: "Manage Data"

"Clear the Cache":

• Settings -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

If clearing cookies didn't help then it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and when present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data