[Can someone start and stop my server?]

Hey.  I was playing on my server when it kicked me.  Now it keeps starting up and stopping and I cant join.  Can a hacker do that?  pls help thanks.

[Hacker on a rampage]

Thank you so much for the support!

[Hacker on a rampage]

All my builds are gone because I reset the server

[Hacker on a rampage]

I just joined back after restarting the server but can someone please explain how that happened and get this guy banned?  Thanks. 

[Hacker on a rampage]

Hey So I recently started a peaceful server with lots of builds and we were just having a fun time.  I enabled some command blocks for some fun builds when this guy called Gypsyjazz begins spamming "mob bombs" of some sort and spamming foreign characters in the chat.  Then I banned him.  HE JOINED BACK AGAIN and filled the world with lava.  I banned him again, and then he joined back and banned ME!!!  I unbanned myself in console and banend him and joined back but he kept banning me.  So I tried stopping the server and putting up a watchcat.  Did not help.  I turned off command blocks.  Somehow he was able to keep unbanning himself.  Now I can't even start or stop the server anymore.  Please help and ban this guy.  He destroyed a really good server.  He was also hacking other people's messages and portrayed as me and started spamming the N-word, along with some of my friends as well.  What should I do?  I feel really devastated.

[Completely made the server unplayable and repeatedly banned me]

The username is gypsyjazz.  HUNT HIM  DOWN!!!!  My server got completely thrashed

he kept banning me