URL is not working

Hello

I had a wordpress.com blog and I decided to move to .org and install it through MAMP on my mac. Everything was working great and I successfully managed to transfer my wordpress.com to my new .org website….. And then I stupidly messed with the URL section within general. I entered a domain that I own into the “site address” section (thinking it might be that straight forward!!) and saved it. It obviously didn’t work so I changed it back to the original and that doesn’t work now either?! I’m so confused.

I’ve tried basic things like logging out, restarting MAMP and still nothing. Any advice would be greatly appreciated!!!

thanks!!