Launcher and Vault Cache disappeared ! [4.11 Preview 6]

I have been using 4.11 for a while without any problems and have stuff in the vault cache since the 4.1 days. Recently I downloaded the NVIDIA’s Hairworks branch from Github and was trying it out. It was still at 4.10 but hair bit was all fine till I suddenly realized that the launcher had disappeared. The entire Launcher directory and the vault cache was gone. Elsewhere in the Answer hub I did see someone else complain that the launcher disappeared but that was with the early Windows 10 preview. I have the proper release version. Any ideas what happened ?