While your server is online and running ARK creates multiple backups that you may use to easily roll back your server's world to a previous version if needed. Below are a few steps to get you working in the right direction. Before you begin, take note of the active world you're using. Any instances of <worldname> below would be replaced with the name of your active world.
To roll back your ARK server's world:
1. Log in to your server control panel and stop your server.
2. From the left-hand sidebar, choose FTP File Access and then go to the location /ark/ShooterGame/Saved/SavedArks/.
3. Locate your backups. The file called <worldname>.ark is your currently used world that will be loaded on startup. For example with TheIsland, the file would be named TheIsland.ark. All other files with dates and times after the world name are your backups.
4. To restore a backup, rename <worldname>.ark to <worldname>.ark.backup, to store a copy just in case you'd like to use it another time.
5. Pick any of the backups in this folder and rename it to <worldname>.ark, so that the file you just previously renamed is replaced by this backup file.
6. Restart the server and the backup world will be loaded up.