Steam
Steam
It seems the system is blocking online access and only lets you connect offline. It looks like your internet connection or router might be faulty. Can you try restarting your modem/router or check your internet service provider's status?
Occasionally things work their way back into place. Think about using a platform like GOG to avoid losing access to your items.
They offer games without relying on online DRM solutions, such as Dunevo.
Use Task Manager to force close Steam and then reopen it; this usually resolves most issues. If not, it may fix itself on its own.