Loop through the form's Controls collection setting each control's Enabled property to True or False.
Note that some controls do not have an Enabled property (for example, Shape controls) so the program must use an On Error statement to protect itself.
Note also that you can disable the entire form by setting its Enabled property to False. Unfortunately that disables everything on the form including the form's system menus so the user cannot close it. The form's controls also look like they are enabled even though the user cannot interact with them.
Similarly you can disable the controls inside a Frame by setting the Frame's Enabled property to False but the controls still look enabled.