It was quite sad that Nokia Devs forgot to update the adb drivers after the update. The update also updated some configurations within adb and fastboot and as the drivers didn't have these updated configurations, they refused to be installed. But I'm still breathing so I made it happen.
1. Download Latest ADB Drivers from below and extract it's contents on to your desktop (or anywhere you like).
2. Connect your Nokia X/XL with USB Debugging On. (Settings-->USB Debugging).
3. Windows 8 users, you need to follow this guide to turn off signature verification. This is necessary as I cannot sign the drivers. Windows 7 users also have to do this by following this guide.
4. For Windows 7: Press Start and in search box, type "Device Manager" and open it.
For Windows 8: Use Search to find "Device Manager" and open it.
5. Now, under other device, right click the Nokia X with yellow triangle and choose "Update Driver".
6. Browse to the Nokia X Updated USB Drivers folder in the zip package. And let it install.
7. After some time, it will install and Nokia X ADB Composite drivers will be installed.
8. Do it for the other Nokia X with yellow triangle as well.
- Nokia ADB Drivers 13.9.14 : Added missing compatibility.
Just copy the adb_usb.ini file found in the package to C:/Users/<Your username>/.android and replace the previous one (if any). Done!
Enjoy and now, you can use Nokia X Manager and flasher. Cheers.
-A friend who gave me this idea