Can’t log in to admin

I changed the permalink from sing4himministries.com to lonnienorwood.com to experiment. I tried to revert to the original, sing4himministries.com, but was immediately locked out of my admin page, receiving page error messages.

When I clicked on the log-in link from my homepage, i received the following message: Firefox can’t find the server at lonnienorwood.com.

I read the forum messages pertaining to changing folder settings through FileZilla, but I was unable to log in there, as well. When i tried my username and password, I got the following error message: Command: USER lnorwood8325
Response: 331 User lnorwood8325 OK. Password required
Command: PASS *******
Response: 530 Login authentication failed
Error: Critical error
Error: Could not connect to server

Technical assistance is quite dire at this point. Thank you in advance for your time.