The brute-force way of doing it is:
ps waux | grep screen
Find the pid and then do a
kill -9 on it...
Otherwise, try these command-line arguments to screen:
Do not start screen, but instead detach a screen session running
elsewhere (see section 8.1 Detach).
'-d' has the same effect as typing C-a
d from the controlling terminal for
the session. '-D' is the equivalent to
the power detach key. If no session
can be detached, this option is
ignored. In combination with the -r/-R
option more powerful effects can be
Reattach a session and if necessary detach it first.
Reattach a session and if necessary detach or even create it first.
Reattach a session and if necessary detach or create it. Use the first session if more than one session is available.
Reattach a session. If necessary detach and logout remotely first.
Attach here and now. In detail this means: If a session is running, then reattach. If necessary detach and logout remotely first. If it was not running create it and notify the user. This is the author's favorite.
Attach here and now. Whatever that means, just do it.
Note: It is a good idea to check the status of your sessions with screen -list before using this option.