Precision m3800 - touchpad drivers not working

Hello! Since about two weeks I am having problems with touchpad in my Precision M3800. (Btw sorry for writing about it in this thread, but I didn't found a specific one for Precision laptops). It stopped working once, with no reason. I tried every 'conventional' methods of solving this problem, and while all failed, I uninstalled my touchpad drivers and installed new ones from dell webpage. None of them are working, either. At first attempt it even was not possible to install them. The installer always said that my PC hasn't been rebooted after uninstalling Synaptics drivers and that I should restart it. Reboots, of cource, never worked. Then I noticed that after every restart, system always installs missing Synaptics drivers. They are in C/program files/synaptics. They are in this folder (with app delltouchpad.exe, which can be sometimes opend, but doesn't controll touchpad and doesn't save any changes made in settings), they didn't allow any new drivers to be installed. So i used a program called IObit Uninstaller that deletes apps with all its remainings. It deleted the driver and I was able to install new one. It didn't help either, the touchpad is completely dead.

For sure it is not a hardware issue - I ran a preboot diagnostics. They are controlled by touchpad and it was working propertly here.

Please help me, I am desperate... It isn't a problem when I have a mouse with me but without it... Operating pc only using touchscreen is bloody inconvenient...