See the java thing. If you do have it, then you can try looking for the LW preferences and deleting them. Relaunch preferences.
If that won't work, unistall Java, go to
www.java.com, download and install the latest version. Restart LW.
If that won't work, try opening LW by dbl clicking the .jar, not the .exe.
If that won't work, uninstall LW, and download the latest beta LW. See if it works. (If it doesn't try all of the above with it)
If that won't work, I think it's time for you to try another client, unless some has something else for you to try or I'm forgetting something.
PS: Good luck and be patient