Rixxles

I was notified by my friends then when they try to start up the server with /join (name), they had trouble with starting it up. When I went over to the dashboard, I realized the server was in offline mode. So I click 'Start' and it says "starting" for 10 seconds, but then it goes back to offline mode. I have tried repairing files but it still doesn't work. If you know how to fix this or how to download the world files without being in the server, please let me know!