How to get back accidentally deleted `wpa_supplicant` file?
The wpa_supplicant.conf resides at the location /data/misc/wifi/wpa_supplicant.conf. Since it is inside /data/, rest assured that it is not lost for eternity. It would take factory reset to bring it back from scratch. 

Also, that file contains device specific and your once connected Wi-Fi's specific information. So, there is no point for us to upload it for you.