If you press FN and F3 at the same time again the light above the touchpad will turn off meaning the touchpad is now enabled.

Notice at the top of your touchpad an orange light came on this means your touchpad is disabled.

First press and hold the FN key and then press the F3 key at the same time.

This will allow you to enable or disable your touchpad. You will be taken to a screen where you can control many aspects of your computer. The My Computer icon lets you access everything from drives to documents. In this instance, we want to enable or disable the touchpad if you notice on the F3 key there is a picture of a touchpad with an X through it. If you can change settings by gsettings, generally it is the preferred option.Since you can enable/disable touchpad from System Settings, and I am pretty sure System Settings does use gsettings, it looks like the method below should do the job, on your Dell as well. How to Disable the Touchpad on My Dell Laptop Step 1. The FN key allows you to use those orange icons.

Now take a look at the top row of keys on the keyboard there is a row of keys starting with the letter F (F1, F2, F3, F4.) on each of these F keys there is an orange icon.

It is located at the bottom left corner of the keyboard to the right of the CTRL (Control) key.

NOTE: While this model is no longer sold by Micro Center or the manufacturer, this information may still be useful to those using this model of computer. This article will show you how to enable and disable the touchpad on a Dell Inspiron 15R Notebook. How to enable or disable the Touchpad on a Dell Inspiron 15R Notebook - Micro Center

How to turn off touchpad on dell laptop