How to change file system ntfs to ext4?

Question

ubuntu

Restored Windows, and when restoring Windows changed the file system of all partitions, including the Ubuntu partition to ntfs. As a result, when you try to start Ubuntu, grub is launched, on Ubuntu the sources of the desired site.
In grub, I specify with the commands set prefix hd0,1 set root each of the partitions (I have 5 of them) after the search /boot/grub command writes that no files were found ...
What do you advise?
Z.Y. I think that Windows not only changed, but deleted the Ubuntu partition...

Answer 1

she erased everything, if there are no files, just rearrange ubuntu