Can access 127.0.0.1 but not localhost?

What operating system are you on?

mmm, sounds like your HOSTS file doesn’t have localhost listed in it. i’m not sure exactly how but i think you just need to add “localhost<tabspacehere>127.0.0.1” and that should make localhost point to 127.0.0.1, and if i remember rightly, the HOSTS file on windows is inside C:\windows\

Good luck.

“Have you tried turning it off and on again?”
seriously switch off the networking in device manager and bring it up again. I can’t think of a way to accidently get rid of the loopback in hosts.