If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, DuckDuckGo PE, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content. You can click shield icon for more detail and possibly disable the protection. You can check the Web Console for relevant-looking messages about blocked content.

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

You can try these steps in case of issues with webpages:

You can reload webpage(s) and bypass the cache to refresh possibly outdated or corrupted files.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 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 -> [X] Cached Web Content -> Clear

• https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox
• https://support.mozilla.org/en-US/kb/how-clear-firefox-cache

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

Dear sir,thankyou so much for your advise.I tried as what you suggested,but my FB messenger still the same,I can't type anything except click the Thumb Up icon or upload any file or pictures.Even in comment of any posts also the same,can't type any comment BUT I can type to anyone reply in any posts. All just happen 2 days ago.I reported to FB but no reply or whatsoever. Really much appreciate if you can assist further.Thankyou and have a good day.

Is there a reason for the old version of Firefox? https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Dear Jon, Firstly sorry if address your name correctly,thankyou for your asistance. Yes,I need to use the old version cos my office server is running on WindowXP 32 bit.Worst come to worst I have to buy another pc just for FB.Really a waste of money and office space.

All these happen just the last 2 days before this it's all fine.Wonder what FB done to it with their update.

I still can upload pic or files or even click ThumbUp or any Gif pic,ONLY cannot type any texts in the Messenger or comments in anyone posts.If to reply to anyone posts,it can.It's weird really.

Really appreciate if you can assist further or anyone face such problem.

Hi there. If you're still using 52.9 ESR, you can try to enable service worker in about:config. Go to about:config, accept the risk, then type "dom.serviceworkers.enabled" (without quotes) and press enter. It will show the preferences, toggle them from "false" to "true". After that Restart your browser and try again.

If it still doesn't work, you can try to use m.facebook.com (the mobile version of facebook, it supports old browser better and faster)

I understand how you feel. I didn’t like where Firefox Quantum was going. So, I stopped updating at v54. So far, no real issues. And I still have my Legacy add-ons.

I have noticed, however, that some websites don't work properly.

Last resort: Delete browsing, search and download history on Firefox {web link}

Remove a single website from your history {web link}

Open the History Manager <Control> (Mac=<Command>) <Shift> H. In the search bar, enter the name of the site. Right-click on one of the listings and select Forget About This Site. This should remove all information, including any site settings And Passwords.

Dear FredMcD,do you mean that I should enter the site name of Facebook and select Forget About This site? Thankyou.

Just follow the instructions I posted.

Did you try the mobile version of Facebook as posted above as it is possible that Firefox 52 is no longer supported ?

Dear cor-el,I tried the mobile version,it works,thankyou.

Dear FredMcD,I tried your method to delete the history,but it's the same.The problem is still cannot type any texts either in comments or Messenger.Thankyou so much.Really appreciate it.