I’m in the same boat - my pro micro was working fine, then it stopped. I am very pleased to see from this thread that there might be a way forward by re-burning the bootloader.
Still, i am interested in why this happened in the first place. Would anyone care to comment on what they think they did to cause this? Can a rogue sketch corrupt the bootloader - i had thought not?
Personally i had foolishly tried to configure all the digital pins from 1 to 20 plus as outputs and then pulse them to try and find the one that was connected to the TX LED (only now do i realise that there isn’t one). Perhaps this had somehow caused the problem?
When i power up the Pro Micro the two LEDs flash momentarily, which i thought meant the bootloader was ok - but i can no longer get a sketch to load (the IDE (v1.0.1) times out and the LED’s do not flash). Yet i can program other boards with this setup.