If your Touchpad stops working after it has been left unused for awhile, it may be due to runtime power-management. Disable runtime power management of the Touchpad device and check if the issue persists.
Look for your Touchpad device in /proc/bus/input/devices.

The line starts with S: is the path of the Touchpad device, the full path will be something like /sys/devices/platform/i8042/serio1/input/input5/power/control.

Disable runtime power-managed by running echo on | sudo tee /sys/devices/platform/i8042/serio1/input/input5/power/control (replace the path with the one for your Touchpad device.

If the problem disappears, report as such to your bug report. If the problem persists, read on.