Gazebo doesnt open and there is no error message

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Hi

I am new to this so please excuse if this is a newbie problem, when I use the gazebo command nothing happens

also when I try to start rviz it says:

qt.qpa.xcb: could not connect to display 172.29.48.1:0 qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found. This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, xcb.

Aborted

I used the tutorials of Robotics With Emil from Youtube and someone in the comments recomendet to write:

"source /opt/ros/noetic/setup.bash"

export GAZEBO_IP=127.0.0.1

export DISPLAY=$(cat /etc/resolv.conf | grep nameserver | awk '{print $2}'):0

export LIBGL_ALWAYS_INDIRECT=0

in the bashcr file but it didnt help...

hope you can help me best regards