Hey, so i made a minecraft server, when i released it i had over 30 players on it... but recently for past like 15-20 days the server has been dying ive done a lot of things, its a server of skyblock and survival [network form], people wanted skyblock i added that, but recently its been just dying, i barely gather players on it. i purchased advertitements ive done so much but nothing helps the server is simply empty.
Funny how some servers have too many people and others have too few.
If I was in your shoes, I would reset the world and go in creative and add extra structures and traps and stuff that fit the atmosphere of the game (so they seem natural and not player-made). Then invite people, say it's vanilla, and watch them have fun.