cant open display

As an AI language model, I don't have access to your system or terminal to provide a specific solution. However, the error message "can't open display" typically indicates that the X11 display server is not running or that the DISPLAY environment variable is not set correctly.

Here are some general troubleshooting steps you can try:

1. Check if the X11 display server is running by typing the command `ps aux | grep Xorg` in the terminal. If it doesn't show any output, try starting the display server by running `startx` or `sudo service lightdm start` (depending on your system).

2. Make sure that the DISPLAY environment variable is set correctly by running `echo $DISPLAY`. It should show a value like ":0.0". If it's empty or incorrect, you can set it manually by running `export DISPLAY=:0.0`.

3. If you're trying to run a graphical application over SSH, make sure that X11 forwarding is enabled on both the client and server sides. You can do this by adding the "-X" or "-Y" option to the ssh command (e.g. `ssh -X user@server`).

Hopefully, one of these solutions will help you resolve the "can't open display" error.