I' m trying to install or run variuos Linux Live-Systems(Distributions) on my Laptop:

ASUS ROG g551vw
16 GB Ram
120GB Samsung SSHD
1 Tb Western digital HD
8 Core I7 Intel CPU
4K Display 15''
USB 3.0
Settings in BIOS: Fastboot=off, Secureboot=off, Compatibility mode= on, Legacy mode=on

Neither with DVD nor with USB-stick is it possible to get a System started because after a certain while of loading, the following message shows up:
"Unable to find medium containing live file system" Didn't find a solution in numerous forums.
Does anybody have an idea how to proceed?
every answer is appreciated,
thanks

how are you creating the live bootable media?
in full detail please.

Welcome to LQ! #2 likely has seen this happen with improperly created media.
Can you boot both the dvd and usb ok, on some other computer?
IF so, can you 'catch' bootloader and append parameter: init=/bin/sh ?

A totally different approach is VirtualBox (&osboxes.org)
Simple&quick, you could try multiple distros with/while M$WinX still running!

Thank you for having done web-researching first!!!
(maybe mention which things/keywords didn't solve it for you)

Best wishes; LQ will 'get you there'