HELP With profiles

Help please guys. I cannot seem to get into my wordpress admin account. I have downloaded a new theme but it put the files into my account: Your Car Buyer. I’m not a tech kind of guy so when i started to edit my new one it posted it to my old domain. i have now lost https://www.yourcarbuyer.oc.uk and has been replaced with: https://www.sellit2trade.co.uk and i can’t seem to get into the admin backend to change it back

Hope someone can help me!

Steve

The page I need help with: [log in to see the link]