Converting Text Case in Excel VBA :-

If You want to Convert Text Case in Selection :-

Sub ConvertProperCase()
Application.ScreenUpdating = False
    Dim Rng As Range
    For Each Rng In Selection.Cells
        If Rng.HasFormula = False Then
             'Use this line for ProperCase text; change UCase to LCase for LowerCase text.
            Rng.value = Application.Proper(Rng.value)
        End If
    Next Rng
End Sub

Sub ConvertLowerCase()
Application.ScreenUpdating = False
    Dim Rng As Range
    For Each Rng In Selection.Cells
        If Rng.HasFormula = False Then
             'Use this line for LowerCase text; change UCase to LCase for LowerCase text.
            Rng.value = LCase(Rng.value)
        End If
    Next Rng
End Sub

Sub ConvertUpperCase()
Application.ScreenUpdating = False
    Dim Rng As Range
    For Each Rng In Selection.Cells
        If Rng.HasFormula = False Then
             'Use this line for UpperCase text; change UCase to LCase for LowerCase text.
            Rng.value = UCase(Rng.value)
        End If
    Next Rng
End Sub