Active partition issue, "BOOTMGR missing!"

It was a terrible weekend, when my computer failed to start after a partitioning session on my "external" hard drive. Weird! When the partitioning was over, I knew clicking a dialog box without reading its contents properly. I barely remember that was something related to confirmation for an "active partition". As my conscience directed, immediately did a Google search to see what an active partition is. The results told me that if active partition is wrongly set, the computer won’t boot. Checked the windows partition using the Disk management snap-in and it was not set as active. Quickly set all the three system partitions, C:, System Reserved and Recovery as active partitions and re-booted the PC.

Oops! BOOTMGR is missing! System won’t start. Doomed!

Fortunately I had my recovery disk created some time back and tried to boot from that. System booted and Recovery console opened. Did a System repair and re-booted. No, it didn't boot. Again the same error was reported. Checked about active partition issues using Google on my smart phone (how good to have a smart phone, I love it). So finally found a step by step procedure for recovering from an active partition issue. It is as below.

Launch command prompt from the recovery console and type the following commands.

DISKPART

Diskpart prompt will appear

LIST DISK

Note Disk number of the disk on which windows is installed. On a windows only machine, mostly it will be '0'.

SELECT DISK 0

LIST PARTITION

Note windows partition and use it in place of # in the following command

SELECT PARTITION #

ACTIVE

EXIT

The following screenshot explains.

That's it. Now reboot. No, again BOOTMGR missing! What happened?

OK, most of the pre-installed Windows 7 machines, there are two hidden partitions other than C:, namely, recovery and system reserved as given in the below screenshot.

Which one has to be set active? That was confusion. If I set anything randomly as active and if the recovery disk itself is not getting detected, what am I supposed to do?

Again back to Google. No solution found.

Took the risk of playing around to set the recovery as well as system reserved partitions as active as explained above. When I checked the partition details, I was able to see that only the system reserved partition is active and recovery partition is inactive. So at any point of time only one partition can be active. If one is set active, the others go inactive.

So now, set C: as active and rebooted. Voila! It worked. Now the computer is running fine. So in the process the missing bit is "set the windows partition, say C:, as active" and even with a single drive, in windows 7, there will be two additional hidden partitions - Recovery and System Reserved. The one that needs to be active is your C: and no other.

Here is a full account of things to be done to recover a system from such a situation.

Use recovery disk to boot.

Get into command prompt from the recovery console.

Invoke Diskpart and set the windows partition to active.

Type Exit to close diskpart and exit again to exit the command window.

Remove the recovery disk from the optical drive and reboot.

That’s it.