Sorry for the delay. Yesterday I had the same problem. Now I realized that the flie grub.cfg (or something like that) desappeared from its natural directory (c/ubuntu/disks/boot/grub). Hope this can help. This bug really sucks since ubuntu must be reinstalled.
Sorry for the delay. Yesterday I had the same problem. Now I realized that the flie grub.cfg (or something like that) desappeared from its natural directory (c/ubuntu/ disks/boot/ grub). Hope this can help. This bug really sucks since ubuntu must be reinstalled.