are you useing ie??? if so rigth click at top in grey area and select address bar. this should put address bar back in. if that dont work, then it could be a possiblr virus or trojan attack, have you scanned for viruses,trojans, and spy/adaware???
dont feel bad my dad's boss had same thing happen to him, him it was navigation buttons.
if you are using oprah,firefox,or safari i really dont know for sure but this above should be generic for fixing problem.
hope this has helped
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