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PC randomly changed system drive, bootmgr.exe missing

by nigalo / February 24, 2015 10:46 AM PST

My computer randomly changed my system drive letter. On the system repair menu, it says windows is installed on E:\Windows.. it should be C:\.

When I use diskpart and then list volume, it shows that the SSD that I have windows installed on has changed to E:\, the other non-SSD drive is now C:\, and theres a 100MB partition that is now D:\ (it used to not show up on "My Computer"... There used to be just C:\, D:\, E:\ (external hdd), and F:\ (Bluray/DVD/CD drive).
The 100MB partition is the only active partition.
I tried changing all the volume letters, but they all revert to how they are rn. I set my SSD to C:\ and switched it to active which gave me a "bootmgr.exe missing" error that I dealt with for a couple hours (fixed that by booting the windows 7 disk and running repair... which only worked when I booted from the CD drive normally (there's a UEFI option and another option, if I booted from UEFI, the windows 7 repair tool says its not compatible with my version of windows.))

When I type list disk, it shows the SSD where windows is installed as Disk 1 and the other HDD as Disk 0. My files are intact my SSD, I checked with "dir".

I tried this command: F: ->cd boot->dir->bootsect /nt60 SYS /mbr, which executed successfully but didn't do anything.

I tried "bcdedit /export C:\BCD_Backup->c:->cd boot->attrib bcd -s -h -r->ren C:\boot\bcd bcd.old" which gives me a file not found error, even when I change C:\ to D:\ or E:\.

bootrec /fixmbr and /fixboot both work but don't do anything. Bootrec /scanos and /rebuildbcd both don't detect a windows installation. However, when I was getting "bootmgr.exe missing", it DID detect windows but on running /rebuildbcd, it told me "system drive not found"

I can't reinstall windows without reformatting...

please help me, this is totally random. The only thing different about my computer since I last rebooted it is a few skyrim mods from skyrim nexus. Sad

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by nigalo / February 24, 2015 11:30 AM PST

K, I went ahead and reinstalled window... any idea why this happened?

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Something to know.
by R. Proffitt Forum moderator / February 25, 2015 12:12 AM PST

Drive letters move when booting to another Windows. So if you boot from DVD/USB the letter change. Also if you boot from another drive, the letters change. It's been this way for 2 decades. Not much new to add here.

It's more accurate to write that drive letters are assigned as Windows boots.

So the drive letter may not be C if we booted as you shared above. This will confound many but it is NOT A BUG. It's a Windows annoyance.

It's not that random but you could force this by unplugging all but what you think is the C drive.

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