[SOLVED] Delphi 2007 can't start anymore

Delphi 2007 can't start anymore. I 've tried re-installed many times but still not working.

You are probably encountering the following issue mentioned on the Delphi Wikia page:

If you get the error "root element is missing" when you start the Delphi 2007 IDE, this can be caused by a corrupt file EnvOptions.proj, located in the Application Data\Borland\BDS\5.0 subdirectory of your profile. Move this file somewhere else and restart the IDE. If that was the problem, the IDE will regenerate the file and work again.

Delphi 2007 can't start anymore - root element is missing