See second post.
From memory, when you follow the guide, it puts the ATMEGA16U2 into a different mode so that the Atmel/Microchip loader can program it over USB.
Can you show us a photo of the bottom of your board.
It seems that @simplylegend0046 has reached the limit on posts for a new user. Here's the image of the bottom of the board that they have just set me via PM:
Any idea what the "10k resistor" is connected to?
Unfortunately, the link didn't explain beyond "put one end here and the other here".
I've no idea, but this link seems to say it is to do with the HWB line ???
It also indicates that the resistor is not needed for an UNO R3.
@simplylegend0046 if you follow the steps in the guide in the second post ignoring the step with the 10K resistor, then you should get the ATMEGA16U2 into DFU (Device Firmware Update) mode. It should appear in your device manager when it's in DFU mode.
Sorry i dint find it im new to this User interface the one which says nRF24L01 Pipe addresses.. ?
And yes sorry for no reply i was unable to reply for 17 hours and thanks @markd833 for putting those images for me i thanked you but i think even messaging was disabled
So i connect these with a jumper wire and the TX 0 and TX 1 ?
This is kind of complicated.
The Instructions say to briefly short them together, nothing about tx/rx in this regard. A jumper wire (F/F) will make things easier.
My suggestion is that you pore over that document, taking notes.
Have I missed something ... when did we start talking about radio modules?
No i asked you for the link and you told me to see your second post
Er, which second post did you look at? When I said:
I was referring to the second post in this discussion. 
if i click on your account
this is your second post right?
Ohh My bad
so i should solder the 10k resistor but where ? can you mark it ?
Oh .... I see the confusion 
Anyways, back to your issue. You should plug the UNO into your PC so it powers up. Then short those 2 pins out with the jumper cable like you have. Then remove the jumper cable. The ATMEGA16U2 should then be in DFU mode and should appear in your device manager. I can't recall what it appears under, but the FLIP software should find it and generally Windows should play a sound when it detects the ATMEGA16U2 has connected.
Re the 10K resistor, looking at the photo of the rear of your board, yours is a Rev3 board, so you don't need it.
mm so i did what you asked like i plugged the UNO board to my pc through the usb and i used the jumper and removed the jumper while its plugged in but still nothing happened in the device manager nor i heard a sound even if i like plug my mouse or something like pendrive sound comes and also a notification, do i need to download something ? i just tried using different usb cables to now i tired 3 of them still nothing seems to happen
You need the FLIP software. Follow the link in my post #2 in this discussion and scroll down to where it says:
Download a DFU Programmer
There's a link to the Microchip website that will take you to the FLIP software download page. You may also need to download the Java Runtime Environment (JRE) if you don't have it installed already.
I'm wondering if there may be something terminally wrong with your board as I was sure that Windows showed it. I just watched this Youtube video:
At around 4 minutes in, they show how to short out the pins. They also talk about grounding one side of a capacitor but I don't see any reference to doing that in the official Arduino docs so I would be wary of that advice. You do hear their PC playing sounds as the Arduino board connects and disconnects.
I would try and get your Arduino to appear in Device Manager first before downloading any other software.
Tried this 2 times but still i dont get a thing in device manager