Hi Nicole,
From your description, I suppose you are using Office 365 for Professionals and Small Businesses, have I got this right?
If so, in order to access your team site directly by clicking Team Site button on the header of portal page. I suggest you perform the following things to change the team site URL back to initial.
Access your team site with an Admin account->click Site Actions->click Site Settings->click Title, description, and icon under Look and Feel section->change web site address, type “team site” in the dialog box->OK, for example:
Thanks,
Maggie Li