Check the 30amp fuse on the relay to the rear (left) of the battery. That provides 'always on' power to the ignition switch.
Also check the connector attached to that relay. Make sure that it is structurally sound and that the terminals are clean and not corroded.
Remember that one of these leads and terminals is live, straight from the battery with no fuse protection - so having visually checked, don't be tempted to go probing without disconnecting the battery first.
If that fuse has blown, the next question should be 'why' ?