How can I access /storage/emulated/0/DCIM on android device?

The "/storage/emulated/" folder does not really exist. It's what might be called a "symbolic link", or, in simpler terms, a reference to where the real data is stored. You'll need to find the actual physical location on your device where it is stored. Since it's in /storage/emulated/0/DCIM/.thumbnails, it's probably located in /Internal Storage/DCIM/.thumbnails/. Please note that that this folder probably only contains "thumbnails", which are very small versions of the real files. It's possible your real files are gone forever if your SD card is irrecoverable.

Edit: "Never Say Never" The link actually refers to an emulated SD Card on your device. Access the data "directly"* as the SD Card, and you will have access to all the data on that card. *Airdroid's file "app" will allow this. And, if memory serves, access via a USB data cable will also.

I could recover my files by going to "Settings -> Storage and usb -> Images -> Camera. There if you select a photo then the right side top menu changes to "Select All" and "Copy to..". First select all, then copy to a folder like "downloads" or whichever is visible in explorer. Once copied to the desired folder. Copy from that folder to your Computers folder.