if you are using mods, I don’t think the game will load a save without them in the correct folder, but this is a launching problem so that is probably not it, but make sure if you have mods you put them in the correct place and they are up to date
in steam right click stonehearth and left click properties go to tab local files and left click browse local files if you are using the x64 version then go to that folder and left click Stonehearth.exe to select it then right click it to open the context menu and left click properties, go to the compatiibility tab and check the box Run this program as an administrator and click ok. then try playing again
I would also run steam as admin as well, just to be safe. other issues might include your computer time being out of sync with steam and a thousand other things.