You can check: *https://support.mozilla.org/en-US/kb/fix-video-audio-problems-firefox-windows *https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues *https://support.mozilla.org/en-US/kb/html5-audio-and-video-firefox ----- If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block (wanted) content (e.g. Adblock Plus, NoScript, Ghostery, uBlock Origin) always make sure such extensions do not block (wanted) content. *make sure your extensions and filters are updated to the latest version You can try these steps in case of issues with web pages: You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files. *hold down the Shift key and left-click the Reload button *press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux) *press "Command + Shift + R" (Mac) Clear the cache and remove the cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences). "Clear the cache": *Options/Preferences -> Advanced -> Network -> Cached Web Content: "Clear Now" "Remove the cookies" from websites that cause problems. *Options/Preferences -> Privacy -> "Use custom settings for history" -> Cookies: "Show Cookies" Start Firefox in <u>Safe Mode</u> to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem. *switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance *do NOT click the "Refresh Firefox" button on the Safe Mode start window *https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode *https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems