If your Windows 7 PC fails to boot, or just has trouble starting up for whatever reason, there are a few simple steps you can take to recover your current operating system without having to re-install from scratch. You will need your Windows 7 Installation media to perform the steps show here.
While your PC is on insert your Windows 7 installation media and reboot your PC, and from the Windows recovery environment select system recovery options, and the system recovery tools menu. From here you should start by running the “startup repair” process. We will warn you though, this process is very slow! If you were unable to recover with this method or if you prefer to use a faster method, select command prompt from the recovery tools menu.
At the recovery tools command prompt enter “bootrec /fixboot” without the quotes and press enter. This writes a new boot sector to the Windows system partition, repairing the boot files required for the system to start. Viruses have been known to target windows startup files, in some cases deleting the boot files altogether. This will effectively rewrite these files for you. You can also use this approach if you installed Windows 7, and then installed a previous Windows version which will cause Windows 7 to no longer boot anymore. Windows versions must be installed in the order of previous versions first! If you are dual booting with Windows XP and Windows 7, you will need to install XP first. If you are having problems here make sure the command prompt is pointed at volume C:/. You can change your directory to point here by typing “CD C:/” without the quotes.
At this point you should attempt to reboot your PC and see if the boot up process is now functioning. Messing with Boot Configuration Data store in the next step can cause issues and should done last.
If you suspect a corrupted master boot record is the culprit you can rewrite it with this:
bootrec /fixMBR and press enter
At the command prompt type:
bootsect.exe /NT60 all and press enter
This parameter updates the boot code on all bootable partitions, you can also type: "bootsect.exe /NT60 sys" (without the quotes) to recover the master boot code for the main system volume only.
These parameters attempt to repair the current BCD store without overwriting it. You can also attempt to rebuild the entire BCD from scratch with this:
Bootrec /rebuildBCD and press enter
If Windows is unable to locate your BCD store you may need to manually rebuild the BCD itself like this, pressing enter after each step:
bcdedit /export C:\BCD_Backup
attrib bcd -s -h -r
ren c:\boot\bcd bcd.old
The attribute parameters will remove the hidden, system, and read only attributes giving you full access to the current store, in which you can delete and rebuild as this is what these commands will do.
If you don’t have a Windows 7 Installation disk you can create one in from within Windows. Click start, select system and maintenance, and backup and restore. Now select “create a system repair disk.” You will need a blank DVD to perform this function. It’s a good idea to have one just incase something goes wrong. While most PC manufacturers include a recovery partition to restore from, not all do, so it’s a good idea to have a recovery disk when you need one.