Hi naveen, You should take a look at the Knowledge Base article [[Search bar]]. Your default search might have been changed by a particular site. Sites like MSN, Yahoo, etc have been know to ask to become your homepage and change your search engine. If the address bar search has been changed as well, you might want to take a look at [[Location bar search]]. If that doesn't work you should look at the article [[Preferences are not saved]]. We've also got a [https://support.mozilla.org/en-US/kb/removing-babylon-searchqu-or-mystart list of common search related issues] that might be helpful. Finally, your issue may be because you've been hit with some [https://support.mozilla.org/en-US/kb/Is%20my%20Firefox%20problem%20a%20result%20of%20malware?s=malware&r=0&e=sph&as=s#w_how-do-i-get-rid-of-malware Malware]. Hopefully this helps!