First, you should check whether you have any add-ons that might have made that change. You can review all your extensions on the following tab and disable all that are nonessential or unrecognized, then restart Firefox.

orange Firefox button or classic Tools menu > Add-ons > Extensions category

Next, to reset your default search provider back to Google, you could try this extension:

https://addons.mozilla.org/en-US/firefox/addon/searchreset/

Does that work?

"Add ons" disable did not work but default search provider reset did. Much appreciated. Thank you very much.