If you're on an MP server, it's likely that you were too close to a chunk that a server admin reset. Most likely you can't get anything back so in the future you will want to build farther from towns, roads, traders, POIs, to avoid your base being in an area that gets reset. Typically there are no "Perfect" spots that are far enough from everything.
If you can get anything back, you will probably need screen shots of your chest contents, work station inventory, etc so that they know what you had before reset. Without that they won't because it's an easy way for players to get free stuff.