touchpad and keyboard doesn't work

This can be a simple fix such as updating firmware on your computer. Check your user settings and see if there are any available updates in the Microsoft update wizard, then execute appropriate updates.

If there is not a patch given in the software side of things you may need to do some work inside your unit.

Check out the repair guides provided on the device page for the Dell Latitude 7350.

There is a guide labeled for the issues presented. If there is not one check out the other model number listed in the Dell Latitude 7300 series.