Click the Firefox button, go to Add-ons, then Extensions and remove "Loudmo Ad Assistant"

Thanks for the suggestion which I tried and looked for but unfortunately found no mention of "Loudmo Ad Assistant" anywhere in "Add-ons, then Extensions".

OK, please do the following then.

To revert to Google as your preferred search engine, please do the following.

• In the location bar, type about:config and hit Enter.
  
  
• In the filter at the top, type: keyword.URL
  
  
• Double click it and remove whatever's in there and replace it with http://www.google.com/search?q=
  
  

The URL to add in "keyword.URL" becomes a link in this post, so right click it and choose "Copy Link Location" to copy it to the Windows clipboard. Then hit CTRL+V to paste it. Saves you having to type the whole thing.

To reset your home page, do the following.

• Go to the site you want to set as your homepage.
  
  
• Click the orange Firefox button and go to Options | Options | General.
  
  
• Make sure it says "Show My Homepage" in the first dropdown menu.
  
  
• Click the button called "Use Current Pages" to set the homepage to the one you have on the screen.
  
  

After you complete the above steps, install this add-on to prevent another search engine from modifying your preferences: https://addons.mozilla.org/en-US/firefox/addon/browserprotect/