Deleted my server files! (Mac)

I was going to try to update my Bukkit server from 1.11.2 to 1.12 so I downloaded the most recent bukkit and did the whole start.command thing. I then ran the server but it gave me this: [WARN]: **** FAILED TO BIND TO PORT!

I then decided that I couldn't figure it out so I just deleted all of the files for it off of my Mac and tried to use the old server (Version 1.11.2). However, when I try to run the old server, I get the [WARN]: **** FAILED TO BIND TO PORT! thing again.

Also, when I go onto Minecraft and go to multiplayer, my server is up and in the 1.12 version but I can't use any commands or change the server.properties or any files because I don't have them for the 1.12 server. Is there any way that I can use my old (1.11.2) server again or close the 1.12 server that I tried to set up?

 

@_Kicker19_
Most likely, you still have the 1.11 server running when you are launching the 1.12 version. Go into your task manager, click processes, and end all JavaW processes. After that, try restarting your server.

If that does not work, please post the full console log here.

 

@_Kicker19_
In case you were unaware, the task manager for macOS is called Activity Monitor. You can also just restart your computer to stop the server.

 

I ended the Java thing in Activity Monitor and the 1.11.2 server runs now but I can't connect to it. I get the Minecraft error: java.net.ConnectException: Connection refused:

--EDIT--
Fixed it (restarted the server)

Thanks for all of the help guys!

 

@_Kicker19_
Please mark this thread as Solved if the problem has been fixed.