My 4th generation kindle won't appear on my PC when connected via USB. I've tried two different cables, tried turning on and off the kindle yet still nothing. I need to be able to connect it as I haven't used it for a long time so need to manually install new updates via the PC.
Please try changing the USB port where you connect the Kindle. If you use a fixed PC, use the rear USB inputs to see if it is recognized this way.
As a further suggestion, try to connect your Kindle to a different PC. If the device is recognized on another PC, you can check if your device is updated to the latest software version. If necessary, update your device to the latest software version available, and try connecting it to your PC again.