Hi,
If you have not tried some of the following: Running the Relational Database Curriculum in your Browser Please do so.
You may end up knowing that what you have to do is either restart your VM/container and worst case delete it and start over (i know this is not what you want) as options are limited.
In case you have to do a “hard reset” i suggest saving your progress (queries, commands and any other thing that is executed either in the psql/bash terminal) in a separate file so you can “recover” faster from this if it happens again.
This happened to me several times so it’s better to make some backups of whatever you need to continue from where you left when this happens.
Hope this helps.