Here is a step-by-step explanation I used to restore the boot information,
it is taken from the Web:
1) Boot from Windows 7 installation DVD
2) Choose "Repair Your Computer"
3) Click the operating system that you want to repair, and then click Next.
(if no Windows operating system is listed, click Next anyway)
4) Click "Command Prompt"
Next:
At the command prompt, type diskpart.
This will get you to the DiskPart prompt, which allows you to use a variety
of hard disk partitioning and formatting tools similar to FDISK in older
versions of Windows.
At the DiskPart prompt, type select disk # where the # sign is the number of
the hard disk drive with windows 7 installed on it. If your windows drive
is the only hard drive in your computer, it is Disk 0.
Select the partition by typing select partition # where the # sign is the
partition that has windows installed on it.
Type active and press ENTER. The windows partition is now active. Finally,
type 'exit' to close DiskPart. Reboot the computer using the windows 7 dvd
and follow steps 1-6 above. You can now repair the windows boot:
Fix the Master Boot Record: (commands)
bootrec /fixmbr
bootrec /rebuildbcd
bootrec /fixboot
5) Reboot your system. The problem should be gone now.