Don’t use your usual password, as the method used is pretty weak (standard DES)
Open a screen session :
Inside the session press ctrl + a then type :password
If successfully set, you should see [ Password moved into copybuffer ] in the lower left corner of the terminal.
Now you can detach by pressing ctrl + a then d
Reattach with :
$ screen -r
And now you should be prompted for the session password.