This can be a real problem and normally occurs if you’ve installed a keyboard replacement, set it as your default and for some reason it’s stopped working. You can resolve this with a Hudl2 Factory Reset however this will result in the loss of all your data.
There is another option. Firstly make sure your Hudl2 is fully charged. You’ll need to plug an OTG cable into the Hudl2 charging port. The acronym OTG stand for “On the Go”. An OTG cable essentially allows you to connect a USB device (in this case a keyboard) to you Hudl2. OTG cable can be purchased for a few pounds and look like this:
Plug a USB cable into the USB female end of the OTG Cable. All being well, you will now be able to type your password into the Hudl2 to unlock it. Go to Settings->Language and Inputs->Current Keyboard and select English (US) Google Keyboard.