import webbrowser
webbrowser.open('C:/Users/300231823/Desktop/GUI/simplenew4.xls')

from win32com.client import Dispatch

xl = Dispatch("Excel.Application")
xl.Visible = True # otherwise excel is hidden

# newest excel does not accept forward slash in path
wb = xl.Workbooks.Open(r'C:Users300231823DesktopGUIsimplenew4.xls')
wb.Close()
xl.Quit()

>>> app = xw.App()  # or something like xw.apps[0] for existing apps
>>> app.books['Book1']