Or have you been victim of spy ware of other sites who has changed your default search engine setting in Firefox ?I faced the same situation so, I would like to help you get rid of this.
1) Go To Location Bar -- about:config and press enter key
You will either have one alert box or will go direct to all configuration settings of Firefox.
-For alert box click on I Promise
.
Now in all results filter your results by searching "keyword.URL." you will have one one result like pair of Key /Value. change its value to url of default search
engines and you are through :)
Now get relax and enjoy your search easily.
