why is the email address no longer recognised

Hi, my husband's Hotmail email address is no longer recognised when he tries to sign in even though it's normally used on a daily basis.  He haven't been able to access it for a few days and he has just rang microsoft for support who said his computer is full of viruses and he would have to pay £250 for a year to rectify the problem.  It's not his computer that's the issue because I can't access it from my computer either.