You'll need to check the cable connection between the touchpad and mainboard -- service manual linked below.

https://www.dell.com/support/home/en-us/product-support/product/vostro-15-7510-laptop/docs

@ejn63​ 

Hi, I can't find a manual on checking the cable connection.

I have already ran the diagnostic tool as shown in the "Fixing Your Laptop Touchpad not Working in Windows" manual.

My current suspicion is that it has something to do with the IC2 HID driver, that became faulty due to a windows update. 

I have tried every suggested solution I could find online, but the touchpad is still not working.

Try removing that update and rebooting the system -- if that doesn't solve the problem, you'll find the instructions you need in the section on removing the palmrest assembly (which contains the touchpad).

https://www.dell.com/support/manuals/en-us/vostro-15-7510-laptop/vostro_15_7510_tglh_sm/palm-rest-and-keyboard-assembly?guid=guid-4aaea62d-3f30-4e6e-adec-ad46b79b8ea6&lang=en-us

@ejn63​ Uninstalling the update and rebooting didn't help. Updating again didn't change anything either.

Are you saying it's a hardware problem?

Unfortunately, I'm not comfortable opening up my laptop myself.

One last thing you can try is powering off, unplugging the system and removing the base cover and disconnecting the main battery from the system board.  Hold the power button for 30 sec, reassemble and test again.

More than that and yes, a hardware repair is needed.