Testing a touch laptop or 2-in-1
Open the page in Edge or Chrome and tap Start dead-zone test on the display itself. Cells here are larger (about 64 pixels), because a laptop panel is wide and a fingertip dragged across it should light whole cells instead of leaving thin unlit slivers between strokes. Work in horizontal passes from the top, then a few vertical ones; give the bottom row, next to the hinge, a slow pass of its own.
On a 2-in-1, test in laptop and in tablet position: the screen is the same, but folding or detaching changes how you hold it and which edges you reach. If you reach for the touchpad by habit, the page notices, keeps a note on screen and labels the result as mouse input, so a shared link can’t claim a touch test that didn’t happen.
When the touch screen doesn’t respond
Microsoft’s steps start with a restart, then installing Windows updates, optional updates included (in Windows 11: Settings > Windows Update > Advanced options > Optional updates). Next, open Device Manager by right-clicking the Start menu, expand Human Interface Devices, right-click HID-compliant touch screen and choose Disable device, then Enable device. If more than one touch screen entry is listed, do it for each one.
On a Surface, Microsoft also suggests booting into UEFI and touching the screen there: if touch doesn’t work in UEFI either, the touch screen has most likely failed and needs a service order; if it does, the cause is probably Windows or its driver. For a laptop from another maker, contact that manufacturer.
Sources: Microsoft Support: What to try if a touchscreen doesn’t work, Microsoft Support: Enable and disable a touchscreen, Microsoft Support: Surface touchscreen.