Choose to Forget internal storage, how to recover

I'm using Moto G 2nd Gen with Android version 6.0. I was using an external SD Card as Internal storage, and I guess it has encrypted the card. Recently, my phone started to work abnormally. It randomly fails to recognize the storage. After a device reboot, it would work for some time and fail again. In the "Storage & USB" settings menu, I clicked "Forget" on the external SD card. Then I realized I cannot access the data from my computer using the SD card reader. How can I re-plug the SD card back as Internal Storage without formatting it again?