I have a bootable USB disk. There is a program in the USB disk for controlling a micro-controller. Yesterday my friend did a big mistake. He connected the disk to his laptop, and after creating backup from files, he formatted the disk. He forget that the drive is bootable, and the program must be run from boot, and it can't be run in Windows. Now we can't boot USB disk. Can anyone help us?
If the drive was formatted, there is no easy way to reverse that. You would need to recreate the partition table (assuming your friend created a new one), format the partition(s), then put the software back on the drive.