Why is my 2019 ram 1500 touch screen not working?

There are a number of reasons (and ways) that a touch screen could fail, and that holds true with Your 2019 Ram 1500. When it comes down to it, it really depends on HOW Your touch screen is failing; since You didn't give us that information, I'll try to explore the three major ones. If You're getting an all black screen with no display, You're likely looking at a wiring issue. The unit is not getting power, so it's unable to operate. Alternatively, an all blue screen indicates a software failure. You'll need a dealership to reflash the stock software so that the system can boot once more. Finally, a display that just won't accept touch inputs is likely because of trauma or damage to the digitizer beneath the display screen. You might see a small crack, or maybe nothing at all. Regardless, this is perhaps the moSTSevere, as there's really no way to fix this -- replacement is almost a necessity.