Well, I guess I screwed up royally this time, but I can't remember where.

I have a dual booted system with Debian Wheezy and Windows 8.1, and LVM, which worked fine until I had an upgrade on Debian, after which I did not have a working Debian anymore. I think I screwed up with the upgrade.

Trying to solve the problem I screwed it up some more, so nothing worked anymore. Starting the laptop I would get:
"error: file not found
Entering rescue mode...
grub rescue> _"

I managed to boot Debian again, with SuperGrub, but I have not succeeded to boot from the hard drive, it will only boot with the SuperGrub CD.

I do not know enough to solve this, I have collected some info that might be useful for solving;

root@debian:~# cat /etc/fstab
# /etc/fstab: static file system information.

# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc defaults 0 0
/dev/mapper/MJ-root / ext3 errors=remount-ro 0 1
# /boot was on /dev/sda5 during installation
#UUID=87d328e5-9322-4841-9c41-b50e6a8099d6 /boot ext3 defaults 0 2
/dev/mapper/MJ-home /home ext3 defaults 0 2
/dev/mapper/MJ-swap none swap sw 0 0
/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto 0 0
UUID=87d328e5-9322-4841-9c41-b50e6a8099d6 /boot ext3 defaults 0 2

root@debian:~# blkid
/dev/sda1: LABEL="SYSTEM" UUID="428A3BE38A3BD261" TYPE="ntfs"
/dev/sda2: UUID="CAFE5049FE502FC5" TYPE="ntfs"
/dev/sda6: UUID="jHIhKU-nEh2-qZeb-JwGY-oUP2-7qX7-TVQVCF" TYPE="LVM2_member"
/dev/sda5: UUID="87d328e5-9322-4841-9c41-b50e6a8099d6" TYPE="ext3"
/dev/mapper/MJ-root: UUID="613faf94-a169-480d-b6ee-7c258c4a42a6" TYPE="ext3"
/dev/mapper/MJ-swap: UUID="88376c9b-f3a9-4b99-912d-e969eae76cc4" TYPE="swap"
/dev/mapper/MJ-home: UUID="ab745dc5-762a-4dd3-8b52-167aeefea89a" TYPE="ext3"


root@debian:~# fdisk -l

Disk /dev/sda: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x99f6b6ea

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 409599 203776 7 HPFS/NTFS/exFAT
/dev/sda2 409600 1025726006 512658203+ 7 HPFS/NTFS/exFAT
/dev/sda3 1025726462 1465147391 219710465 5 Extended
Partition 3 does not start on physical sector boundary.
/dev/sda5 1025726464 1026213887 243712 83 Linux
/dev/sda6 1026215936 1465147391 219465728 8e Linux LVM

Disk /dev/mapper/MJ-root: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/MJ-root doesn't contain a valid partition table

Disk /dev/mapper/MJ-swap: 1996 MB, 1996488704 bytes
255 heads, 63 sectors/track, 242 cylinders, total 3899392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/MJ-swap doesn't contain a valid partition table

Disk /dev/mapper/MJ-home: 193.3 GB, 193273528320 bytes
255 heads, 63 sectors/track, 23497 cylinders, total 377487360 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/MJ-home doesn't contain a valid partition table

I hope some genius can help me out here, I am lost...

All I can do is point out the obvious. Sorry. Swap, root and home all do not have valid partition tables. The boot-loader appears to have been damaged or removed, which should not happen during a normal upgrade. I am assuming this was an update and not an upgrade from Squeeze to Wheezy. Do you remember doing anything else?

I am clueless, but shall throw out an idea anyway, in hopes it helps. Since you can boot the system using a SuperGrub CD, how about using it to boot Debian and re-installing grub? Like I mentioned, I am actually clueless. So I do not know if it is a simple apt-get install and update grub or if it requires a more intricate procedure. Good luck.

Yes, you are right, it was an update and not an upgrade.
That swap, root and home do not have valid partition tables apparently has to do with fdisk which is not yet very good with LVM. I looked that up.

SuperGrub can find a grub.cfg file that lives on (hd0,msdos5)/grub/grub.cfg, not sure whether that is right or wrong, but that is the only one, and it boots with that file.

If all else fails I can backup all data and start over again, but I prefer not to! I hope there are better solutions.

And I learned I should not update when I am tired, look what happened!

Well, I will be out of town for a few days, but ideas are more than welcome!

It's all solved, hurray. Somebody mentioned EasyBCD, and that was installed on the windows side, I could boot windows from the SuperGrub CD, let EasyBCD repair the windows boot, then I was back to having Windows boot without problems, but still only a grub command line on the Linux side

Booting Debian Wheezy from CD I did a grub-install and voila, it all works again.

By the way, there are some commands for LVM, like vgdisplay and lvdisplay, I discovered

Thanks, everybody!

Solved!

Somebody mentioned EasyBCD which was installed on Windows, I could boot Windows through the SuperGrub CD, then let EasyBCD do a boot repair, which worked wonderful, so I had Windows again.

For Debian Wheezy I had only a grub prompt still, but booting Debian through SuperGrub I did a grub-install and voila, everything is working wonderful again.

By the way, I found there are specific commands for LVM, like lvdiplay and vgdisplay and some others.

Thanks everybody!