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.
  

no joy. i had already tried the latter part of your solution for the start up page. As i say the setting simply reverts back after i reopen firefox. also i have now changed th keyword url as you suggest.

If you're only changing the home page, but not the "keyword.URL" search, then yes, when you type in a search in the location bar and hit Enter, Firefox will use Bing.

This is not my problem sorrry it is this. I downloaded a screensaver from bing. As a result of this when i start up firefox two tabs are displayed. These are MSN and Bing. I previously had this set to show wikipedia when i start up firefox. When I attempt changing this back to Wikipedia via the orange firefox button and options (which i have done many times before) it does not work. When i start firefox the start up page reverts to the MSN and Bing tabs which I do not want at all.