The issue will either be the trackpad cable or the trackpad, the keyboard will most likely be fine.
First, check both ends of the trackpad cable for burns/corrosion on the gold pins. If there is any, order a cable.
Next, check the trackpad board on the trackpad for corrosion. If there is any clean it.
After this, wait until you get the new cable and try it out. If it is still not working, order a trackpad too.
The trackpad cable has a part number on the bottom of it. 2013/2014/2015 trackpads or trackpad cables will be cross compatible.