[ubuntu] Mounting filesystem from live usb

Hello,

I know there are some threads somehow related to my problem. But reading them did not help.

I try to mount my "original" system ubuntu 14.x via a usb live system (ubuntu 14.04). My original system failed to boot. thats why ...
I tried the usb live system.

In the terminal:

sudo mount /dev/sda1 mnt

... but this seems to be my usb device.

Actually, this is the only one I see if I use

gparted

/dev/sda1 fat32 /cdrom 3.71 GiB 3.5 GiB, 215.61 MiB boot, lba

sudo mount /dev/sdab mnt

does not work as it does not exist.

So, I would be happy to get some support accessing my "original" system.

Thanks Herma