my daughters hard drive was replaced and the activation code does not work. please help.

Hi,

depending on the way you purchased Office, you may have previously redeemed your product key, if so, login to office.com and this article should help:
http://office.microsoft.com/en-us/support/how-do-i-recover-or-replace-a-lost-microsoft-office-product-key-HA104172018.aspx?redir=0

Hi,
Please do a phone activation in Office. The phone activation process will provide you with the appropriate phone number to call. Explain to the service (Human being) that you have changed the hard drive and you cant activate your Office.

You can find your local custom support number on the link below.
http://support.microsoft.com/gp/customer-service-phone-numbers/en-us

Regards,

Greta Ge CHN
TechNet Community Support