I know there a lot of these threads, but none seemed to work for me. So here is my situation. I have an AMD Radeon HD 7850 HIS IceQ Turbo graphics card which has a DVI, HDMI, and 2 DisplayPorts. I have two identical LG 23EA63 Monitors connected to the graphics card using two DisplayPort to HDMI cables. This setup worked well in Windows 10 until the day I bought a mac and wanted to share monitors. So I connected the Mac to one of the monitors using the DisplayPort to HDMI cables, then connected the DVI cable from the PC to the 2nd monitor. So now the PC has monitor 1 connected through a DP to HDMI, and monitor 2 connected by DVI. I decided to get the Mac its own monitor so I disconnected Monitor 2 and put it back on the PC using the 2nd DP to HDMI. Now, the 2nd monitor will not display.

So here's what I have already tried. I uninstalled the graphics driver and CCC by using the clean uninstall tool on AMD's website. Rebooted, then downloaded and installed the latest driver. Still nothing. I have clicked on Windows Key + P and set it to extend, still did not work. I went to Control Panel, chose Troubleshooting and ran the Hardware and Devices troubleshooter. Nothing. So looking in device manager I see that it is only showing one monitor (where there used to be two). When I click on Control Panel and go to Display, it shows two monitors - the first being the correct LG 23EA63, but the second shows "Display: 2. Display device on: VGA". It will not let me make any changes.
So finally I opened CCC and used "Detect Displays". It shows 1 LG23EA63 and 1 Unknown (with a graphic that looks like an old CRT monitor).

So the last thing I did was to unplug both monitors and reconnect each one individually using the each cable to make sure I didn't have a bad cable. Both monitors worked using both cables (one at a time). I then plugged monitor 1 back in with a DP to HDMI cable, and monitor 2 with a DVI, and it worked. Both monitors appear and everything works. But I really would like to go back to using both DP to HDMI for both monitors. It is noticeably better.

Sorry this is so long, I just wanted to be thorough. I would greatly appreciate any help or suggestions you may offer. I am about to lose my mind with this. I even reinstalled Windows 10 to see if that would work!!! (It didn't).