WordPress says my username/email address doesn't exist. How do I log in?

Hi, I’ve messed something up on my wordpress (unfortunately I’m quite new to .org) and I have no idea how to fix it! Here’s the details;

I recently bought hosting with 1&1 and a domain with namecheap.
Until I could get my domain to point to wordpress, 1&1 was using the domain name “s601003897.websitehome.co.uk”.
The domain name “maybemica.com” is now pointing to wordpress (or it was), but my media files all still said they were at s601003897.websitehome.co.uk SO I changed something in the settings to maybemica.com so that hopefully my media files would point there, and www.remarpro.com kept saying “maybemica.wordpress.com doesn’t exist, would you like to register it?”. The page wouldn’t go away no matter what I clicked on so eventually I just said yes. This created the website but logged me out of www.remarpro.com and into wordpress.com (I have an account over there too for a different website, don’t ask me why they’re separate haha) for some reason.

Anyway, now it’s saying my username/email address doesn’t exist on www.remarpro.com and won’t let me log into it, and my website (maybemica.com) is pretty much broken! I have no idea what’s happened or how to get it back, could someone please help?

Thank you so much, I’m having a heart attack over here!