So turns out that i had missed something. in the device manager under "system devices" you have two entries for the intel serial IO I2C Host Controller - A160 and A161 I un-installed them at the same time as the I2C HID device under Human interface devices and then re-started the laptop, this brought the touchpad back in to action. keyboard was however dead. so unistalled all keyboards and restarted laptop. This fixed the laptop in regards to both keyboard and touchpad! only took 6 hours...
Last ditch effort to see if anyone on internet has any experience of the following (pessimistic edition...): Touchpad and keyboard working in BIOS diagnostic and self test. However touchpad was erractic for some time and then stopped working in windows 10 (all updates applied) now the touchpad that is not working, if touched(in windows), "disables" the laptop keyboard immediately. Only way that i have found to re-enable the keyboard is to suspend or restart the laptop. External mouse and keyboard still work if connected through usb. the keyboard backlight still turns on when the keyboard is touched and screen brightness can be controlled together with some laptop functions. but no "input" to windows. when keyboard gets "disabled" there is no change in device manager and if all keyboard drivers are uninstalled and allowed to reinstall, the keyboard is still not possible to "enable" (except sleep or restart laptop) the "disable" of the keyboard happen even when I2D HID device is disabled manually in device manager. I have so far not found a way to stop the touching of the touchpad disabling the keyboard, except when flipping the screen into tablet mode in which case touching the touchpad does not disable the keyboard, unless the touchpad is touched when flipping the laptop back into laptop mode. the device manager is reporting the I2C HID Device (A161) can't start with error code 10  'A request for the HID descriptor failed.' and it looks a little bit similar to the following thread [URL] [URL]#M84385 Dell support assistant troubleshooter for touchpad and keyboard faults are pointless so no luck there. next step fault finding i will try is a linux installation on a stick to see if linux is having the same behavior. of course i have un-installed and removed drivers and allowed windows to try and reinstall them to no avail(might have missed the right one since the naming of drivers are appalling so no guarantee here, have removed all mouse drivers though so...). touchpad setting is missing in windows so installation does no longer recognize the installed touchpad touchscreen and active pen are still working the fact that the touchpad works perfectly in BIOS mode tells me that it is likely some sort of windows related driver or software fault rather than a hw fault. not keen on the nuclear option of reinstalling windows or reverting to an earlier save point since there are to many tales on internet of limited success with those solutions.
XPS 2-in-1 9575 "keyboard" and touchpad problem