Where are the experts? How to Set MBR to start windows?

Where are the experts? How to Set MBR to start windows? -- Linux general technology-Linux technology and application information. For details, refer to the following section. [I = s] This post was last edited by wang1985910

Visita was reinstalled two days ago. After the installation, Ubuntu9.04 was re-installed and upgraded to 9.10.
The partition is as follows:
When visita is installed: [c:] --------->/dev/sda1
[D:]
[E:] --------->/dev/sda3
[F:] --------->/dev/sda4
Four disks. The system is attached to drive C.
When Ubuntu is installed, the disk D is configured and the partition is:
/Dev/sda5 ---------->/
/Dev/sda6 ---------->/usr
/Dev/sda7 ---------->/var
/Dev/sda8 ---------->/home
/Dev/sda9 ----------> swap
Now, after Windows 7 is reinstalled on drive C, restart the computer without selecting a list and use the Ubuntu installation CD for system repair,
When you enter grub settings in shell to load the program, the prompt sh cannot find the grub command (this command is not available in the directory where PATH is located)
How can this problem be solved? How can we re-set the loading program? Please help us with the analysis. It is best to have a more detailed explanation.