If you see "USB Device not recognized," install BlackBerry Desktop Software first. It includes the necessary BlackBerry Virtual Serial Port driver.
If you can tell me you need the flash file (e.g., forgotten password, boot loop, or language change), I can provide more specific instructions on how to use it. blackberry 9790 flash file
Have questions about your BlackBerry 9790 flash experience? Drop a comment in the legacy forums – the community still rides for Team BlackBerry. If you see "USB Device not recognized," install
If your BlackBerry 9790 is bricked/bootlooping (e.g., “BlackBerry 507 error” or blinking LED), you’ll need: or language change)