Make sure the touchpad driver (for example, Synaptics or Elan) installed on the PC is the latest. If not, go to Lenovo support site to download and install. Otherwise Device Settings may be unavailable. Search to open Control Panel --> Mouse. See Where is Control Panel?
In the Mouse Properties window, switch to Device Settings or the Brand name tab.
"Synaptics": Click Enable. Click OK to continue. "Elan": Click Enable Device or Stop Device. Select Disable when external USB pointing device plug in to disable the touchpad when a USB mouse is plugged in automatically.