You will need
  • - a Windows installation disc or a LiveCD.
To start, try to make a partition on the hard drive is active, using the features of the operating system. This method has been tested on Windows XP and Vista, but it is also applicable to Windows Seven. Open the start menu and select Run.
In the box that appears, type compmgmt.msc. Click "OK". Go to the menu "computer Management" sub-item "mass Storage device" and navigate to it. Select "Manage diskmi.
Highlight the partition on the hard disk (or entire disk) that you want to make active. In the right column of this window, select "mark partition as active". In the case of Windows 7 this point will be located in the menu "All tasks". Click "OK".
In that case, if you are unable to access the operating system, use the command line to restore the active partition. Start the Windows Vista installation disc (Seven) or LiveCD for Windows XP. Turn on the command prompt and run it.
Enter the command diskpart and press Enter. Now enter the command list disk, then press Enter. In the working window displays a list of hard drives which will be numbered. Select the section that you want to activate.
To do this, enter the command select disk 0 or 1, depending on the numbers disk. Now type list partition to list the existing partitions on the hard disk.
Select the desired partition by typing select partition 1 or 2. To make this partition active, type active. If you did everything correctly, then after pressing Enter you should receive the following message: "the Partition is marked as active. Restart the computer to check the health of OS.