If your Oculus Rift has suddenly quit working, well, we have good news and bad news. The bad news is, your Oculus Rift doesn’t work. The good news is, it’s a temporary problem.
The problem, according to Neowin, is an expired certificate in the Oculus Runtime Service, which needs to be updated. The file in question, OculusAppFramework.dll, will throw an error to this effect when the Oculus Store attempts to launch.
Source: Security Certificate Issues Disable All Oculus Rifts [Updated] – ExtremeTech