Ok, I've managed to find the solution to this problem myself, and I'm sharing it:
NOTE: This works ONLY for ASUS laptop owners.
1. Go to your ARMOURY CRATE software.
2. There go to your GPU Power Saving and make sure the Standard option is selected. I accidentally enabled the Optimized option, due to which the software disabled my GPU.
And that's it. You now have the GPU visible in the Device Manager. If your GPU name in device manager seems translucent, then you probably need to reinstall the drivers.
Also, thanks to Sumit and Raju, who took their valuable time just to help me with my problem.