My 2.79 was installed to: C:\Program Files\Blender Foundation\Blender\
So I installed 2.80 to: C:\Program Files\Blender Foundation\Blender2.80\
I don't know if I missed a prompt, but the 2.80 install deleted all the files in C:\Program Files\Blender Foundation\Blender\ The ...Blender\2.79 folder was still there, but all the files in that tree were gone as well. As a result I could no longer open Blender 2.79 (which I need until all my addons are ready).
Fortunately I was able to copy C:\Program Files\Blender Foundation\Blender\ from a backup.
**System Information**
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.35
**Blender Version**
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: `rBf6cb5f54494e`
Worked: (optional)
**Short description of error**
[Please fill out a short description of the error here]
**Exact steps for others to reproduce the error**
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]