Runtime error '28'..... out of stack space solution!!

Is there any other code resides in your workbook?

You have to disable events before updating the contents of the sheet otherwise the event will fire again.
As your code does not check what cell is changing the event fires and executes the code every time a change happens.

Private Sub Worksheet_Change(ByVal Target As Range)
    
    Dim Events As Boolean
    
    If Range("A4").Value = "GRTP" Then
        Events = Application.EnableEvents
        Application.EnableEvents = False
        Range("A1").Value = "ASIA"
        Application.EnableEvents = Events
        Range("A5:P47").EntireRow.Hidden = True
        Range("A127:P164").EntireRow.Hidden = False
    ElseIf Range("A4").Value = "MMIT" Then
        Range("A5:P47").EntireRow.Hidden = False
        Range("A127:P164").EntireRow.Hidden = True
    End If
End Sub

Originally Posted by meus

Hey sixth sense!! i have a macro but don't have other codes in main sheet..

Andy fixed your issue so try Andy's solution

You need to post a file then as it works for me.

I thought I had in my post.

The event fires every time a cell on the sheet changes. Inside the event you change a cell cause the event to fire again. This keeps happening until it runs out of stack space.

The code I added turns off the event listening whilst you update the sheet from within the event routine