Why did the touchpad stop working?

Question

Iron

Hello. The situation is as follows:
I dismantled the laptop to clean it (DNS company).
Didn't do anything out of the ordinary. I opened the back cover and removed the dust, without any liquid. I twisted everything back, turn it on and the touchpad completely stopped working, neither the buttons nor the sensor react. I read in the internet ala press the button fn and f * ... It does not help. Any thoughts on what this might be? The touchpad is also not visible in the device manager.