The disk of the computer went through a disk partition to install Linux. Time later the partition was tried to be deleted. I saw the disk had aprox 5 partitions and only one was deleted and the computer was then restarted. Then the message >unknown filesystem. grub rescue> showed up. The technician that did the partition did not know what to do and is telling me about an usb boot to restart the computer. Unfortunately he is not very keen on fixing what he did. Is there any way I can do it myself?