recover MBR

For dual boot installation.

http://www.sysresccd.org/SystemRescueCd_Homepage

dd if=/dev/sda of=mbr.bin bs=512 count=1

http://www.digitalcitizen.life/create-usb-memory-stick-system-recovery-tools

http://www.sevenforums.com/tutorials/20864-mbr-restore-windows-7-master-boot-record.html