There are a couple of ways, but the easiest way is probably just to use a For Each loop on the Form.Controls collection. Of you examine each control and check if it is a button, it's a simple matter to enable / disable all of them without referencing the names at all.
"Can you provide me a simple code please ? for winform not WPF.."
Public Sub EnableControls(controls As Control.ControlCollection, enable As Boolean)
For Each c As Control In controls
c.Enabled = enable
EnableControls(c.Controls, enable)
Next
End Sub
Then call it from your Form class with:
EnableControls(Controls, True)