built-in mouse pad is not working

I have a XPS13, which I have only had a few months. Today, it was very sluggish starting; the circle of dots went round interminably until I lost patience and did something else. I came back and found it was now showing the desktop, so I connected to my Kobo e-reader in order to charge its battery and take some new books on board. It was only then I discovered that the mousepad wasn't working. I have no idea how to get it going, and I can't find a way of bypassing it by typing on the keypad instead.

The difficulty is that I'm not supposed to disconnect the Kobo until I have clicked on the eject symbol, so now both machines are stuck and helpless. Presumably there is a technical solution to all this, but in the meantime I am typing this message on my desktop.