Changing domain name mess up!

Hello,
I recently bought a new domain name off of godaddy and was looking to change it under WordPress. A person in a previous thread, which is now closed, had suggested

“As far as changing the domain of your WordPress site, you can do this inside WordPress settings. Change your WordPress Address and Site Address to reflect your new domain. Anything that uses those fields will automatically update. If you have content that hard links to locations at the old domain you’ll need to update that. I’d recommend using Search & Replace for this.”

I did this, it did not work, and now I cannot get onto my WordPress desktop at all! I can access my website using the previous domain name, but when I try to go the admin page, I just get redirected saying “The web address you’ve requested isn’t working.” At this point, I do not care if it’s the old address, https://www.ieltsforuae.com, or the new address, https://www.totalielts.com, I just would like to be able to access my site desktop to make changes etc…

Thank you in advance (by the way, I have very little knowledge regarding this stuff so the simpler the explanation the better :-))