Microsoft Excel: This function checks if a Worksheet exists by accepting a Worksheet name as a parameter and looping through available worksheets. It will return false if the name is not found, otherwise it will return true if a Worksheet with the passed parameter exists. It is case-insensitive.

ExcelWorksheetExists.bas

Function WorksheetExists(wsName As String) As Boolean

  Dim ws As Worksheet
  Dim found As Boolean

  found = False
  wsName = UCase(wsName)

  For Each ws In ThisWorkbook.Sheets
    If UCase(ws.Name) = wsName Then
      found = True
      Exit For
    End If
  Next

  WorksheetExists = found

End Function