im new in vb.net please help me to enable and disable form using MDI thank you

There are three ways you can do that (as far as I know).
1: On the child form you can enable or disable a form in the designer.
2: In the code of the child form, you can type: Me.Enabled = True/False
3: In the code of the MDI container, you can type: <childform instance>.Enabled = True/False

Just make sure that the child form is not modal, in case you need to access it's parent form.

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