Please provide the logs as well, you may remove identifying information.
Also, any displayed error messages, they may seem cryptic, but they are important!
Apache: depends on your ErrorLog directives, but primarily stored in: /var/log/apache2/error.log http://httpd.apache.org/docs/2.4/logs.html#errorlog(http://httpd.apache.org/docs/2.4/logs.html#errorlog)
IIS: http://stackoverflow.com/a/6426399(http://stackoverflow.com/a/6426399), also: http://serverfault.com/a/144054(http://serverfault.com/a/144054)
If you have a hosted server, please consult the help/kb's for your host to find the logs.
Find the logs (note time)
Copy back to before the error occured.
Remove anything that would identify you (hostname/ip/companyname etc)
Post directly if small, or use (pastebin), EG: http://pastebin.com/Hjbs4i7v(http://pastebin.com/Hjbs4i7v)