Unplug the system, remove the base cover and disconnect the battery from the system board.  Check the battery carefully for signs of swelling -- if it's at all swollen, remove and dispose of the the battery immediately. The system will run on AC power until you can order a replacement. If there is no sign of swelling, while you have the battery out, check to make sure the touchpad cable is connected to the system board. If you need a service manual reference, post the full system model number (Inspiron 3593, 3501, 3567, etc. -- on screen in Setup, F2 at powerup).  
My Dell started acting up and the touchpad just stopped working. In device manager the touchpad is not showing. I am at a loss as to what to do. 
Dell Inspiron 15 3000 touchpad not working