What I call the shell is that black screen with white letters, where you can execute commands. Can you execute commands? A check list is useful:

- Check hardware, disk and memory

- What "programs" are running? you could use htop, ps or any tool to learn what are running in your pc.

- Check logs to find the root cause.

- If you identify the logs of your programs, try to stop and start these program and read what the log said.

- Use a search like duckduckgo or googlespam to look for common errors.

- Start with the minimum, just run the OS without all the other programs, it's working? ok.. start bitcoind... it's working? ok... start LN node... and so on. Disable any extra layer of complex software.