Sometimes the driver is present but hidden.
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Power users disabling “unknown devices” in Device Manager may mistakenly disable Acpi Fnbt0000, not realizing its purpose. Acpi Fnbt0000 Driver
Acpi Fnbt0000 Driver is a specialized system component primarily designed to handle communication between the Windows operating system and a device's Function Buttons (FnBT) via the Advanced Configuration and Power Interface (ACPI) Sometimes the driver is present but hidden