I am connecting from Windows with Putty and XLaunch to a Debian machine version 7.6, I have tried it on other machines and it worked, the problem is the Debian machine itself, not the configuration. I have already tried this:
DISPLAY=:0.0 xhost localhost
The last command tells me that it is unable to open a display.
NOTE: I'm on a Windows system attempting to use XLaunch to remote display an X application from the Debian system, to Windows.