Hass command not found

hello guys,
I have been using the home assistant over my pi for more than a month. Today i have reinstalled every thing including the hassbian os . At first the hass --open-ui command is working fine and i am able to access the gui from another system. Then i made some changes in the config.yaml file and then rebooted the pi then i am getting the following error when i am using the hass --open-ui command.
Its showing bash: hass: command not found.
Any idea why it’s not working?

There’s a service to start Home Assistant for you, so you shouldn’t need to start it manually. If that’s not working you’ll want to investigate why.

This explains how to activate the venv, which you need to do before running hass.

Or just

sudo systemctl start [email protected]