Central locking of my VW Lupo 1.0 model 1998 is not working from the driving side but from the passenger side central locking working fine. Any idea? Most recently the power window from the driving side is also stop working. I have no idea how to fix it, any guide with some picture will be highly appreciated.
Is the speaker in that door working correctly? You may well find the flexible wiring connecting the door to the car is damaged or rubbing, causing some of the wires inside it to break or short. I'm not familiar with the Lupo, but some cars of that age have that as a removable section which can be unscrewed and replaced, others it is a more difficult job.
In particular check at the ends of the wire where it passes through the metal into the door or car body, as they often use a rubber grommet which can fall out and allow the wires to rub.
As an example, this shows the wiring in a modern BMW door:
(photo pinched from a Google search)