Yup, as I suspected .. probably nothing you typed, more likely that for some reason when you ran "sudo update-grub", something went wrong and t wasn't able to rebuild the GRUB menu properly.
As I said, try a reinstall .. it's unlikely to happen again, but if it does we'll track the problem down

Unless of course you'd prefer to work it out now .. but it will likely take longer than a reinstall .. up to you
