• step to mount LVM logical volumn

sudo apt-get install lvm2 #This step may or may not be required.
sudo pvscan               #Use this to verify your LVM partition is detected
sudo vgscan               #Scans for LVM Volume Group(s)
sudo vgchange -ay         #Activates LVM Volume Group(s)
sudo lvscan               #Scans for available Logical Volumes
sudo mount /dev/YourVolGroup00/YourLogVol00 /YourMountPoint

in case of live CD/USB boot, skip the first line, apt-get command

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reference
https://unix.stackexchange.com/questions/339011/how-do-i-mount-an-lvm-partition