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so I am new to how to do these, so I apologize if something I say is not how things are done here.

So I have been using Ubuntu 18.04 for a while now. Recently I wanted to try and dual boot LineageOS to just play around with it, and I think I may have damaged my Grub files (or whatever it is called). I have tried to force boot the partition with Ubuntu on it, but I keep getting the same error.

Grub rescue> ls
(hd0) (hd0,msdos1) (hd1) (hd1,msdos1)
grub rescue>set boot=(hd0,msdos1)
grub rescue>set prefix=(hd0,msdos1)/boot/grub
insmod normal
error:unknown filesystem.

I tried the same thing with set root=(hd0,msdos1) but that got me the same issue. I tried both of these variants with (hd0), (hd1), (hd1,msdos1), and got again the same errors. I am unsure of what to do at this point because I have gone through a lot of different things to try and fix this issue and none of them have done anything. Any advice or suggestions are welcome, and I appreciate all of it!

Note: I did try to boot off of a live USB, which gives me a blank screen, and if I try to boot it through Grub rescue ((hd1,msdos1) is its file system) and I get the same error through Grub. If there are any questions at all feel free to ask, and thank you in advance.

TheBlinded
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  • what do you mean "i did try to boot off of a live USB, which gives me a blank screen"? what was involved in those steps? – WU-TANG Jul 21 '20 at 23:35
  • Unknown filesystem usually is the wrong partition... First ensure which partition you want to boot from ls (hd0,0)/ ls (hd0,1)/ ls (hd1,0)/home/ etc..etc... until you've located the correct one (you can just use the number).... Also take a look at what returns from just typing 'set' – WU-TANG Jul 22 '20 at 00:03
  • @WU-TANG: First Comment: I went to the bios setting, and changed the boot order to boot my USB first so that it automatically would try and boot my USB key. In that process, I get a menu that asks if I would like to try Ubuntu without installing, install ubuntu, or check the disk for malfunctions (Or it was something along these lines). If I clicked any of the options, it would have a splash screen of some numbers in the corner, and then go to a black screen, where there is no response. Please let me know if there is any more info I can give. – TheBlinded Jul 22 '20 at 05:28
  • @WU-TANG: Second Comment: I will try your first suggestion when I have the time (It is late as I am writing this, so it will have to wait till the morning) but as for the command "set" output, I get this: cmdpath=(hd0) prefix=(lvmid/h1gqcw-ntj0-gciK-2Doa-XdKn-YMQa-4DG2FV/OBg9xz-gk30-aMsG-SNOc-SLFS-HBTQ-LTsxzj)/boot/grub root=lvmid/h1gqcw-ntj0-gciK-2Doa-XdKn-YMQa-4DG2FV/OBg9xz-gk30-aMsG-SNOc-SLFS-HBTQ-LTsxzj

    I am not sure what any of this means, but when entering grub rescue, I get error: disk 'the same strand as prefix and root here' not found. Entering rescue mode...

     – TheBlinded Jul 22 '20 at 05:35
  • @WU-TANG: I just want to also thank you for your response. I have been trying to fix this issue for a few days now, and have just taken it as a learning opportunity rather than fix a broken PC, so any advice or suggestions you have given me are greatly appreciated! So thank you again! – TheBlinded Jul 22 '20 at 05:36
  • @WU-TANG: Hi, sorry for the fairly late response. I tried out your second comment, and for what seems to be everything, I get the error "unknown file system." When trying to use the command cat, it says "unknown command 'cat'." If I try any combination of these things I get an unknown file system error like before. With /etc/fstab I am not exactly sure what you meant by feel around for fstabs actual location (I am fairly new to all of this, so I apologize) The command cat /etc/fstab says cat is still unknown, but ls /etc/fstab says the disk 'string ID here' not found. – TheBlinded Jul 24 '20 at 21:53
  • 'cat' shows the content of a file, but it looks like it is not available in rescue. yeah i wrote that wrong, but it looks like it is not working anyway. I deleted it. What I meant was ls (hd0,1)/etc/fstab... but it does not seem to be recognizing the drive that way. You may have to use the long string above or something like (lvm,XYZ....). It's hard to describe this here.. I don't know what your "play around with" entailed... First thing is getting the filesystem to respond, if it still will... the other thing i would do is try to get the live USB to boot. – WU-TANG Jul 24 '20 at 22:27
  • Look at these 3 links... they have more detail and tests than I can describe in this box. https://askubuntu.com/questions/142300/how-to-fix-error-unknown-filesystem-grub-rescue ...the "already answered" link on that page has the procedure on what you need to do to fix grub once you get in your system. This describes the LVM references, again, sorry , i don't deal much with LVMs and I can't find a lot out there as related to grub. https://forums.centos.org/viewtopic.php?t=52090 ...and this is for your screen https://askubuntu.com/questions/832163/black-screen-when-loading-ubuntu-live-usb – WU-TANG Jul 24 '20 at 22:42

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