Run Apple Diagnostics
(I'm assuming you have at least a late 2013 MacBook Pro)
One of the best tools in your arsenal is Apple Diagnostics. It will run through a battery of tests to see if there are any issues with your hardware. From a powered off state, turn on your computer and hold down D until the diagnostic screen appears.
If errors are detected, it will give you a code - trackpad codes are
NDR004 - be sure to write it down, whatever it is as your failed trackpad may be a symptom of something else (possible, but not likely). It is also likely that your trackpad has failed and there is no error code - I have personally seen this condition.
You can get more info from the following links on Apple's Support site:
Replace the Trackpad
The good news is that the trackpad is very inexpensive (trending at less than $40 at the time of this post) and easy to replace. iFixit.com has an excellent step by step guide but basically it involves taking off the back cover and removing the battery to gain access to the trackpad.
In my personal experience, every trackpad issue I have encountered has been a failed trackpad (I managed a private school IT department with about 1,500 MacBooks) I have yet to encounter a failed trackpad due to anything else (like a logic board).