This item is your CD/DVD installation drive letter.
If bootrec /fixmbr and bootrec /fixboot doesn’t work, try restoring the boot sector code of your Windows 7:
The fixmbr utility software will repair any damage to the master boot record. If the “Are you sure you want to write a new MBR?” message appears, press Y and hit Enter
The Master boot record is created when you first install Windows, on the first partition you create. The MBR (stands for “Master boot record”) is a boot sector (a region of your hard disk) that holds information about the partitions of your hard drive and acts as a loader for the operating system you’re running. 2 Fix the MBR with Easy Recovery Essentials.