Implement C# Api to synchronize local db with Server Db

I have a c# window forms app developed. I just need one functionality. This app uses local DB for data. I have same DB on a hosting. I want some one to write c# API and deploy those API at server. Let me describe the schema of database. It is actually a data base for a POS System. This system allow user to create multiple stores and 1 warehouse. Inventory can be transfer from one store to another. It works fine in local DB. What i want is: I want to deploye that local db to each system. It means i have 3 systems running that app and have that DB at local. I have a DB of same schema at server. I want some one to write API for push and pull the data from each system to server db. And keep all db synchronized. If you have any question i can clear it. I need it urgently like in 24 hours.