I have checked out many tutorials for elevators, but everytime I make one in a map, they dissappear. Does anyone know what I might be doing wrong?

you probably read this in the tutorials also, but the elevator must start at its highest point.

I believe that if you want to make the elevator go down, you point the brush upwards whereas if you want the make the elevator go up you point the elevator downwards.

Also i dont use func_plat or whatever.... for that you would need to script in order for it to go back and it's more trouble than it's worth. No, make it a func_door instead.