ROS crashed after rebooting the computer

Platform: Ubuntu 16.04 and Windows 10 in my double system.

After rebooting, every ROS command didn't work. Errors like as follows. They continuously happened.

the program 'rospack' is currently not installed. you can install it by typing: sudo apt install
the program 'rosrun' is currently not installed. you can install it by typing: sudo apt install
the program 'roscore' is currently not installed. you can install it by typing: sudo apt install
......

So I rebooted my computer again. Same errors.

Problem solved by shutdown it rather than reboot it.