I have read the various entries that cover this subject. I too have a problem whereby the Apache "It Works" screen comes up, but any attempt to access 127.0.0.1 or localhost/wp (or localhost/ampps ) fails with a 404.
I am not aware of any changes that I have applied other than allowing updates to OSX Mavericks.
When running "sudo /Applications/AMPPS/apache/bin/httpd" I get:
[Sun May 25 08:33:09 2014] [warn] NameVirtualHost 127.0.0.1:443 has no VirtualHosts
(48)Address already in use: make_sock: could not bind to address [::]:80
(48)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs
can anyone shed any light on this? (I have rest the to the default configuration and restarted Apache to see if that helped - but it made no difference).