Keyboard not working - model SVF15N72PGB

First of all, check it works with an external USB keyboard. In the short term that might be your work-around.

I don’t see a disassembly guide or video for your particular model, but they’re all much the same. Take a look at a few for similar Sony models and you should be able to see how to remove the keyboard. Sometimes it’s secured by one or more screws screwed through from the underneath, and sometimes you might have to remove a bezel between the keyboard and the hinges. But if you’re lucky it may just be a case of releasing the clips along the the top (or the bottom) of the keyboard. You can then gently lift it and angle it either forwards or backwards in order to access the ribbon connector which connects it to the motherboard. You might just need to reseat the ribbon in that connector (check from the videos etc how to release the clamping bar - it’s delicate). Otherwise, having got that far, replacement of the keyboard is easy - they’re quite cheap. Just make sure you get one of the correct nationality and for your precise model of laptop. But - without wishing to discourage you - bear in mind that it might be a motherboard fault, which would be much harder to diagnose and fix.