Missing Drive 0 in some utilities suggests PC may fail to reboot

My Win7 PC has been running reliably for 9 years now and, despite the problem I'm reporting below, remains functioning apparently perfectly even now.

A few days ago I suddenly noticed strange symptoms that made me think the machine might not reboot if I shut it down, so I'm running it 24/7 while hunting for a solution...

The PC has a single internal Western Digital 1TB HDD "Disk 0" with two equal partitions:
"C: (Local Disk)" carrying the OS and program data, etc.
"K: (Volume on C:)" carrying user data.

In addition the PC has a permanently-connected external Samsung 1TB USB3.0 HDD "Disk 1" also with two equal partitions:
"M: (Ext. HDD)" carrying incremental system backups and system image
"N: (Volume on M:)" carrying local user data backups (that are also backed up remotely)

The strange symptoms are as follows:
- Under DISKPART on the command line, list disk shows no Disk 0 at all and instead begins with Disk 1 (the external disk) and list volume shows Disks M: and N: with their capacities, etc. but no C: or K:
- Administrative Tools > Computer Management > System Tools > Device Manager > PC > Disk Drives, shows the Western Digital HDD with its correct model number, but when called for, the error message "Volume information for this disk cannot be found" appears.
- Under Administrative Tools > Computer Management > Storage > Disk Management, Disk 0 is missing entirely, but Disks M: and N: are shown.

However, the following seem to indicate that all is well:
- In Control Panel > All Control Panel Items > Administrative Tools, the contents of the computer are listed in the left pane. Here, just as is also the case in Windows Explorer, drives C: and K: can be seen together with all the files they contain. On K: all user data files can be read, written-to and deleted at will.
- Entering chkdsk c: onto the command line results in the message that Windows finds no errors, ending with a (positive) summary of the drive attributes.
- After having installed the program MiniTool Partition Wizard Free, this shows all disks and all partitions to be present and correct (including the System Reserved area with the status Active, C: with the status Boot and K:Vol. on C:). There is one possibly minor hiccup here: Drive C: is labelled "Disk 1" rather than "Disk 0" but I have no idea if that's what this program always does.

I have screenshots of all the above if required.

My question is what should I check or do before giving in and shutting the PC down and restarting it in the hope that it will boot cleanly?

Hello DimWit, do you still have computer on?

It maybe the disk is okay, but the partition has become corrupted. So, what if you enter DISKPART again, then do LIST PARTITION ? Does DISKPART then list all partition?

Hi iko22, yes PC still on and working perfectly (which is just as well because I have lots of stuff to get finished before risking shutting it down).
Here's what I get:

DISKPART> list partition
There is no disk selected to list partitions.
Select a disk and try again.
DISKPART> select disk 0
The disk you specified is not valid.
There is no disk selected.
DISKPART>

If I select Disk 1 instead I can tell from the information given that this is for the permanently connected external disk M:, not for C:

With my limited knowledge I find it odd that diskpart can't find Disk 0 yet chkdsk c: can.

I see a long long list ending with:
3115 File(s) 1,567,373,850 bytes
100 Dir(s) 423,941,988,352 bytes free

Sorry, was at C:\Windows\system32>. Here's the right answer:
C:\Windows\system32>cd \
C:\>
C:\>dir /w
Volume in drive C has no label.
Volume Serial Number is 880A-64C5

Directory of C:\

.tmp [0e743df0b7c931c75b875af45a8d33]
[2dc2f94fdd76547af747dad1dc74] [7ae2c870ec0aa8acbddc27]
[99d97e3412264b44a2d6] [a3934fd2f8c8c9e4d8850b6f]
[adb] [AdwCleaner]
[AMD] [ATI]
autoexec.tmp config.tmp
csb.tmp ctapi_out_gr.tmp
eula.1028.tmp eula.1031.tmp
eula.1033.tmp eula.1036.tmp
eula.1040.tmp eula.1041.tmp
eula.1042.tmp eula.2052.tmp
eula.3082.tmp [f0af19b0309938fa22]
formatter.tmp globdata.tmp
[inetpub] install.ini
Install.log install.res.1028.dll
install.res.1031.dll install.res.1033.dll
install.res.1036.dll install.res.1040.dll
install.res.1041.dll install.res.1042.dll
install.res.2052.dll install.res.3082.dll
install.tmp mbam-error.txt
[MGADiagToolOutput] [PerfLogs]
[PersBackup] [Program Files]
[RaidTool] [Recovery]
RHDSetup.log service.log
[temp] [updates]
[Users] vcredist.bmp
VC_RED.cab VC_RED.MSI
[Windows]
34 File(s) 4,556,556 bytes
21 Dir(s) 423,941,984,256 bytes free

C:\>

Thank you. That is amazing DISK MANAGEMENT cannot see the disk, yet DIR still shows directory listing of your system drive volume.
Question, how did you perform CHKDSK C: when drive is online? CHKDSK normally schedules to execute only on a re-boot (ie when disk is offline).
Second question, which switches did you use with CHKDSK? Did you use CHKDSK C: or CHKDSK C: /f? Had you tried CHKDSK C: /R.
While the operating system is still online you may want to download and run the WD lifeguard diagnostics tool .
While the operating system is online, you might want to use MiniTool Partition Wizard to create a Bootable disk (WinPE-based media with MiniTool Plug-in), and create CD or bootable USB. (I am assuming that the disk itself is okay, and I am assuming that a re-boot will generate a black screen with "invalid partition table" message).
I am writing this quickly as I assume you will want to make a decision soon about turning your computer off.

Also,, make a backup of the dirve. DO NOT clone the drive, as it will copy errors. Instead, create a System Image, either using Windows Backup or a prefered third party tool.

Before you do anything else, backup your data to an external disk.

Whats showing under your Bios setup


Roy