hide & unhide sheet based on dropdown

Hi Alaa

I think you just need to declare the variable MyChoice as a String (which a sheet name is), not Long (a number).  That will work if cell A1 contains a valid worksheet name (e.g. Sheet2).

The code below should work even if the entry in A1 is not a valid worksheet name (with the file you attached- where the sheet name is "input" not "Input"):

Private Sub Worksheet_Change(ByVal Target As Range)
Dim MyChoice As String
Dim sh As Worksheet

Application.ScreenUpdating = False
If Intersect(Target, [A1]) Is Nothing Then Exit Sub

MyChoice = Target.Value

For Each sh In ThisWorkbook.Worksheets
    Select Case sh.Name
        Case MyChoice
            ' reveal MyChoice (if sheet exists)
            sh.Visible = True
        Case Is <> "input"
        ' otherwise hide any sheet which exists (apart from Input)
            If sh.Name <> MyChoice Then sh.Visible = False
    End Select
Next sh

Application.ScreenUpdating = True
End Sub

See attached file.

Hope this works for you.