It is true that not enough data about other cells of the sheet, but let's start with such a procedure (place in the sheet module, not in the standard module!)
Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Me.Range("A1")) Is Nothing Then
Me.Unprotect
Me.Cells.Locked = False
If Me.Range("A1").Value = "Apple" Then
Me.Range("B2").Locked = True
Me.Protect DrawingObjects:=False, Contents:=True, Scenarios:= _
False
ElseIf Me.Range("A1").Value = "Mango" Then
Me.Range("C1:C10").Locked = True
Me.Protect DrawingObjects:=False, Contents:=True, Scenarios:= _
False
End If
End If
End Sub
Artik