Photon P0 (dip style with USB). It had working code load and was visible to my desktop IDE. I hadn’t used it in months. Last night I could not see it in the IDE, so i used setup and was able to run that process. It took my connection in AP mode, let me set it to my SSID, and started running code.
flashes green, flashes faster, goes cyan and my code runs BLUE LED…
Still cannot find it in IDE and after 2-5 minuts it goes belly up with a shange to green breathing and eventually solid green.
tried CLI:
C:\WINDOWS\system32>particle setup
_ __ _ _ _
| '_ \ __ _ _ __| |_(_) ___| | ___
| |_) |/ _` | '__| __| |/ __| |/ _ \
| __/| (_| | | | |_| | (__| | __/
|_| \__,_|_| \__|_|\___|_|\___|
https://particle.io
> Setup is easy! Let's get started...
> It appears as though you are already logged in as jandle@synergisticscience.us
? Would you like to use this account? Yes
! PROTIP: Hold the MODE/SETUP button on your device until it blinks blue!
! PROTIP: Please make sure you are connected to the internet.
> I have detected a Photon connected via USB.
? Would you like to continue with this one? Yes
! The Photon supports secure Wi-Fi setup. We'll try that.
! PROTIP: Wireless setup of Photons works like a wizard!
! PROTIP: We will automagically change the Wi-Fi network to which your computer is connected.
! PROTIP: You will lose your connection to the internet periodically.
? Found "Photon-ELZD". Would you like to perform setup on this one now? Yes
! PROTIP: You will need to know the password for your Wi-Fi network (if any) to proceed.
! PROTIP: You can press ctrl + C to quit setup at any time.
(node:12300) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): ReferenceError: when is not defined
(node:12300) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
C:\WINDOWS\system32>
Try reinstalling the particle CLI and dev tools.
that was a fresh reinstall of cli. By dev tools do you mean the desktop IDE?
Yeah. I was banging my head a couple of weeks ago because my device wouldn’t show up in the devices list, and a reinstall took care of it. 
Usually, if you Log Out and Back into Particle your devices will then show up. It’s happened and helped others also.
well, that might have helped, but uninstalling and reinstalling the tools did not - except openssl is not missing…
and I made the mistake of resetting the keys, so it’s a brick.
You are executing the command from Windows/System32 which is generally not a good idea due to possible permission issues.
It might be installed on your system, but is it also referenced in PATH?
How did you uninstall and most importantly reinstall? Did you use the Windows CLI Installer?
https://docs.particle.io/guide/tools-and-features/cli/photon/#using-windows
sorry, I meant it is missing.
Uninstalled cli with C:…\AppData\Local\particle\Uninstall.exe
Reinstalled with ParticleCLISetup.exe per the web page.
I am an admin and UAC did not trigger on it.
There are no particle tools (no obvious ones) installed to windows/system32 and no files or folders in the time period that might be related.