Try to install Debian onto my home desktop through usb and grub. Seems my partition table was wiped out during the installation. My windows system as well as my personal data on that partition vanished!
I should have backed up my MBR before making this mistake.
dd if=/dev/sda of=mbr.backup bs=446 count=1
(Usual operation is: “dd if=/dev/sda of=mbr.backup bs=512 count=1” Actually 512 byte Master Boot Record consists of three parts. The first 446 bytes is the bootloader code, that’s the part to back up and restore.
There is also the 4 x 16 byte partition table there, and a 2 byte 55aa bootable device signature.)