def METHOD_NAME(self):
    """
    Reset all settings to their default values.
    """
    self.filename = None
    rmgpy_module_dir = os.path.abspath(os.path.dirname(__file__))
    self["database.directory"] = os.path.realpath(os.path.join(rmgpy_module_dir, "..", "..", "RMG-database", "input"))
    self.sources["database.directory"] = "Default, relative to RMG-Py source code"
    self["test_data.directory"] = os.path.realpath(os.path.join(rmgpy_module_dir, "..", "test", "rmgpy", "test_data"))
    self.sources["test_data.directory"] = "Default, relative to RMG-Py source code"