How to add a game over screen

Hey guys i got a problem that i don’t know what should i do the problem is:
like in the main menu level i want to add loading screen but when i did it i can hear the main menu music so i make a
level for loading screen and game over screen would that be okay or there is any way to fix it
and when i click the play button to open level named loading screen it start to make lag and the screen went black so how should i fix it

Why not just make a widget that displays in the level where your game ended and then have a button that takes you back to the main menu.

i Mean if i make a widget in the level i can hear the level sounds and i cant hear the end music for game over i mean is there anything that it can turn the level sounds off?