First of all be sure you have dm-mod module loaded in kernel and your LVM volume activated

Activating a LVM Volume
Activation is easy:

#vgchange -ay
2 logical volume(s) in volume group “hostname” now active

Identifying a LVM volume

Is easy to identify a LVM volume. Just run lvdisplay you will see something similar to this:

# lvdisplay
— Logical volume —
LV Name /dev/randombug/root
VG Name randombug
LV UUID t4wQGA-w9pI-i7Dl-KHFe-224p-SkTM-IsekyZ
LV Write Access read/write
LV Status available
# open 1
LV Size 15.05 GB
Current LE 3853
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:0

— Logical volume —
LV Name /dev/randombug/swap_1
VG Name randombug
LV UUID Vborz2-XwEu-1Mcg-yAdv-H0fr-UuD3-L3HFKf
LV Write Access read/write
LV Status available
# open 2
LV Size 720.00 MB
Current LE 180
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:1

Now you know where is the LVM resides and what device is mapped for this LVM.
First volume is the root filesystem with device /dev/randombug/root and the second is the swap

Mounting a LVM Volume

mount /dev/randombug/root /mnt/lvm