They are showing as plain text of the symbol?

if you can provide the screenshot

My apologies for the delay in replying. The attached shows what I am receiving.

The mouse symbol is replaced with the number 8. The Telephone symbol is replaced with a (. The fax symbol is replaced with a number 2. The envelope symbol is replaced with a + sign.

Sorry, I can't upload a screen shot but yes, the symbols are replaced with numbers and plain text.

To diagnose problems with Thunderbird, try one of the following:

• Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.
• Restart the operating system in safe mode with Networking. This loads only the very basics needed to start your computer while enabling an Internet connection. Click on your operating system for instructions on how to start in safe mode: Windows 8, Windows 7, Windows Vista, Windows XP, OSX

If safe mode for the operating system fixes the issue, there's other software in your computer that's causing problems. Possibilities include but not limited to: AV scanning, virus/malware, background downloads such as program updates.

Do you have View(or AppMenu/View)/Message Body As set to Original HTML?

Thank you for the suggestions but didn't make any difference. Like to try and re-install Thunderbird. Can you direct me to instructions for doing this ?

Yes, View/Message Body/Original HTML on.

In my experience, Thunderbird never displays Wingdings. This font Is not officially recognized by the bodies who set the standards for HTML. It is a proprietary Microsoft font and therefore is not web safe. I've seen it used by web designers who should know better. Firefox, like Thunderbird, doesn't recognize Wingdings either.

Microsoft email clients use Wingdings with gay abandon with no respect for prevailing norms.

Your correspondents should learn how to use Unicode.  ;-)

Will check out unicode. Thanks.