Closed Server Default World

I've been looking around and I can't seem to find the answer...
So, why is it when you restart the server.exe file to, it doesn't load your saved world? I am hosting a private server for myself and a friend. I had previously just been leaving the server running, but when I shut it down last night and tried to start it back up again, our buildings and chests full of goodies were no longer on the planet that we started on. Is there a way to tell the server to load up a specific save? Or do I need to keep the server running all the time?
Thanks!

 

If you run the server on the same computer you play on, it will load up whatever your single player universe is. Check the coordinates. Perhaps you just got bumped to a different world.

 

We are in the same universe and the same planet/same coordinates, etc. The problem is the planet that we setup on has been like "reset" to its original state, ie before we made our buildings and various things

 

Did you leave "gracefully" the game ?
With ESCAP+Quit. Or like a barbarian with Alt+F4 ?

 

Yes, I exited gracefully