I found a similar solution to this question in c# How to Select all the cells in a worksheet in Excel.Range object of c#?
What is the process to do this in VBA?
Sub SelectAllCellsInSheet(SheetName As String)
lastCol = Sheets(SheetName).Range("a1").End(xlToRight).Column
Lastrow = Sheets(SheetName).Cells(1, 1).End(xlDown).Row
Sheets(SheetName).Range("A1", Sheets(SheetName).Cells(Lastrow, lastCol)).Select
End Sub
To use with ActiveSheet:
Call SelectAllCellsInSheet(ActiveSheet.Name)