You're in initrd (=initramfs) emergency shell environment. You should use it to verify the status of your root filesystem. If your root filesystem is LVM-based, you might want to try commands like
lvm vgchange -ay and
lvm vgdisplay to get more information about the status of your LVM volume group(s).
(In emergency shell, the typical LVM commands are all packaged into a single
lvm binary: to use regular LVM commands, add a
lvm <space> prefix to the command you would usually use.)
You can even try and mount your root filesystem manually, and see the error message that probably occurs when you try to do that.