How do I log into my own account?

I set up a online family account on my home pc, but then had to uninstal it.  Now I have sorted out my computer, I want to set up the account again.  I can’t see anywhere where I can log in with my original account details on the ‘let’s set up your account’ page, so when I type them in, it comes back and tells me that the email address is already registered.  Yes, I know, I registered it, how do I get my account back?!