Hello, Welcome to the Community. We understand the frustration of the touchscreen not responding.
There are some simple ways to get the touchscreen working again when it’s frozen, unresponsive, or acting funny. Here are some troubleshooting steps to assist you with your phone touchscreen issues https://www.samsung.com/us/support/troubleshooting/TSG01213974/
Additionally, a factory reset may help resolve any software concerns.
If the issue persists after performing the troubleshooting steps, you can use the following link to find a list of service centers in the U.S. that can do the repair: http://www.samsung.com/us/support/service/location or by contacting customer support at 1-800-726-7864.
For service outside the U.S., please use this link: https://www.samsung.com/us/common/visitlocationsite.html