Hi Ashley,
Could you please provide the complete error message here?
When you say "when i tried to rejoin it", do you mean activate Office desktop application by entering this Microsoft account?
Please try to login to Office 365 portal with this Microsoft account first, and check if the Office product is listing in your MyAccount page.
Regards,
Ethan Hua
TechNet Community Support
I've tried my microsoft account, and I have done that. It tells me it's not associated with that account. Theres no other account it could be associated with.
In this case, if you are sure that you've tried with the correct Microsoft account, my recommendation is to contact the reseller from where you purchased Office 365 or Microsoft Customer Service directly, to have them have a check on your license association.
Regards,
Ethan Hua
TechNet Community Support