How can I go back to original ROM after flashing custom ROM? without back up
I have a 4.1.2 running android phone Brand WANLTON PRIMO X1. Recently i have rooted and installed TWRP recovery mode, I was looking for a 4.2 update & installed a custom ROM as it stated 4.2 but it is was the same 4.1.2 modded ROM with some bugs, Unfortunately when I flashed the ROM I did not keep any backup but now I so badly want to go back to my original ROM. the link image attached
I have tried to do this according to instruction but it can't detect my phone when connected with USB.
Plz Plz provide me solution for this issue, I will be very very grateful to you.
Thanks in advance.