How to restore grub in my case?

Question

linux

I put Ubuntu, then Windu, the hornbeam flew off, respectively. Booting from liveusb: ubuntu
@ubuntu:~$ sudo mount /dev/sda1 /mnt
mount: block device /dev/sda1 is write-protected, mounting read-only
mount: you must specify the filesystem type

Answer 1

mount: you must specify the filesystem type

Well see mount syntax, type fs option -t ...

Booting from liveusb:
[email protected]:~$ sudo mount /dev/sda1 /mnt

So / dev / sda1 with such a load, most likely, is your liveusb, of course, that is write-protected.
And they mount not in / mnt (usually), but some directory in / mnt with the corresponding owner and rights ...
And it also depends on a). what "Windows" and b). as set, by default, partitioning into partitions or manually, if by default, it made you a hidden UEFI partition (100Mb) and loaded through it.
Reinstalling Linux, the easiest way ...
If you really need "Windows" so badly, then it's always easier to put it 1st.

Answer 2

help.ubuntu.ru/wiki/%D0%B2%D0%BE%D1%81%D1%81%D1%82...

Answer 3

Who said that sda1 is the Linux partition?
Here is the grub recovery instruction help.ubuntu.ru/wiki/grub_recovery - use the second option Recovery using chroot