Question Lost access to my Win 7 installation and can't access that partition at all, not even from the Win 10 installation


Jan 15, 2016
When I built my PC, I had only one HDD. It's still split into four partitions (MBR). I installed Windows XP first (it still exists, haven't booted it in years), then I installed Windows 7 on another partition, and the other two were left for data, files, downloads, etc. I was choosing between Win 7 and XP (XP is called "Earlier version of Windows") through the Windows boot manager screen. Everything was perfect until I added an SSD one day (I partitioned it using GPT) and installed Windows 10 on it. It still has only one partition on it - the one I installed Win 10 on. In the beginning everything was fine. As months and years went by though, signs started appearing for me that things weren't going exactly as planned. First, I was choosing between Windows 10 and the other versions of Windows (7 or XP) by entering UEFI BIOS and choosing which device to boot this particular time - if I wanted to boot Windows 10 I was choosing the SSD and it booted automatically. If wanted Windows 7 - I was choosing the HDD and then I had set it up so that the Boot manager automatically boots into Win 7 unless I press a button to stop it and choose XP. This method was seemingly fine for months (as I mentioned) but the HDD was getting really slow for some reason. When I attempted to defragment, it was extremely slow, and it was getting slower every few months or so. Everything else on the HDD was slow as well. In the end, I was starting to have problems sometimes even booting into Win 7. One of the more weird problems I had was, after the initial boot logo of Win 7, then there was black screen with only the mouse cursor appearing in the centre, and this lasted for way too many minutes, and the cursor was the retro one from XP (the longer cursor, not the shorter one which was appropriate for Win 7). Sometimes even it couldn't load into my own local (default and only one) Admin profile/account, and it loaded some kind of generic one without a wallpaper and the Windows XP theme, even though it was clearly Windows 7 with the classic theme. Even when I attempted to defragment (or only scan) the HDD while booted into Win 10, it was only marginally faster; it was too slow to be normal again, and was getting stuck every time in the beginning of the scan for too long. It's as if the HDD was getting scrambled with time since I added the SSD with Win 10 on it, in the configuration that I described. Now, if I try to boot into Win 7, it's stuck endlessly loading on a black screen, and the partition Win 7 was installed on appears as Local Disk ( G: ) (with only "NTFS" below its name instead of the available free memory) when I look at it from Windows 10 File Explorer and I'm not able to open it. This happened after Windows 10 updated itself automatically one day (including a restart during the update). Other weird problems I've had before the total loss of access to the Win 7 installation and partition include:

1. I had to follow a specific order of actions to avoid more errors. If I wanted to boot straight into Win 10 from a cold boot, I could do that without a problem. But if I wanted to boot into Win 7 (from a cold boot), then I had to first boot into Win 10, then restart, enter UEFI, boot from the HDD and into Win 7. If I tried to boot into Win 7 directly, then that error would appear where it forces you to make a Disk Check (with an automatic countdown) before Windows boot up logo appears.

2. The HDD was getting so slow, that quite many times I got the error during Boot Manager that said "Windows failed to start. A recent hardware or software change might be the cause" and something about a possibility of a failing hard drive or an external memory device that was removed.

If I remember about more weird errors/problems, I'll include them later with an edit.

Why I'm sure the cause is not a failing HDD? Because after the total loss of access to the Win 7 partition, when scanning (for defragmentation) the partitions of that same HDD, now after I lost access it's blazing fast, just as if it's brand new. And mind you, it's not only about 5-6 years old, but it's also pretty full. And it still can be that fast. Which, at least to me, proves that the cause is not some kind of hardware failing, but it's rather been some kind of software/partitioning/MFT problem.

I've had only Win XP and 7 on one HDD (MBR partitions) for years. Later, I added an SSD (GPT partitions) and installed Win 10 on it. In order to choose between XP/7 or 10, I had to choose a different boot device from the UEFI menu (instead of the normal way being entirely through Windows Boot Manager). After I added the SSD, the HDD was starting to get gradually slower and slower with time to the point of losing access only to the partition on which Win 7 was installed on. Curiously, after losing access to that partition, the HDD regained its snappiness and speed, as if it was brand new. How to regain access to the lost partition and to Windows 7?


What you write here is pretty much this: The harddrive was obviouly slowly dying, and instead of back up any important data, you go ahead defragment it.

Compare that to a car: You run it empty of engine oil (or cooling liquid), you see what happens, but still choose to take it out for a wild joy ride instead of refill whatever fluid it is short of.

In your case, the drive is probably run so much after initial damage, that file table itself is corrupted.