Yes, I know this error has been answered and solved many times; but I think I know the reason why this is happening (my bad), I just don't know how to solve it.
I was formatting and flashing some USB with 'dd' like:
dd if=myImage.img of=/dev/sdb1 bs=1M
And everything was perfectly fine until I did a big mistake:
dd if=myImage.img of=/dev/sda bs=1M
I tried to dd my /dev/sda filesystem, I got a message like this (not exactly this, I couldn't copy it):
96452+0 records in 96452+0 records out 71383424 bytes (7.1 MB) copied, 60.664 s, 495 MB/s
So I guess it started to overwrite the stuff in /dev/sda, then it crashed and I got this:
So I guess I started writing on the primary partition, and overwrite important stuff at the beginning of the filesystem. After this, I get the:
Error: unknown filesystem grub rescue >
From which I cannot get out of. I have tried the answers of other questions but I can't get rid of it. Any ideas? If you need more info, just ask. It will be helpful!