Ttgjyuk

I've copied from the PuTTY manual:

PuTTY's copy and paste works entirely with the mouse. In order to copy text to the clipboard, you just click the left mouse button in the terminal window, and drag to select text. When you let go of the button, the text is automatically copied to the clipboard. You do not need to press Ctrl-C or Ctrl-Ins; in fact, if you do press Ctrl-C, PuTTY will send a Ctrl-C character down your session to the server where it will probably cause a process to be interrupted.

COPY:
Simply highlight text in PuTTY. Press and keep pressed left mouse button + move mouse to highlight the text you want + release left mouse button and text will be copied to the clipboard.

PASTE:
Just click the middle mouse button to paste clipboard text in PuTTY itself or every other application that has a text prompt. Please note that modern mice don't have the middle 'button' but usually a wheel, so you have to click on the wheel. If you are using a laptop, tapping on the upper right corner of the touchpad should reproduce a mouse middle click.

I had same problem.

Despite suggestion from manual, left mouse button selection for copying text does not work for me.

I had found that middle mouse button does the trick.

Simple; just highlight the text in putty and right click. Note, though, that this will also paste the text into whatever you are working on in Putty.

For example, if you are copying text from Vim or Nano, highlight the text you want to copy, right click it, and then quit without saving.

You can use cat Abc.java to show the content of file.
Then highlight the text and CTRL + C to copy the text.

After that, you can paste any where you want.

There is an ugly way that I use to copy from Putty console.
In Putty configuration window, I have enabled Session Logging to get the console output dumped to a file on my system.

Then I tail the log file in a local terminal with command:

tail -f <logFileName>

When I have to copy something, I go to the local terminal where the log is being tailed and copy what I need with CtrlShiftC.

just highlight the text on the terminal and click both right and left buttons on your touch pad simultaneously.

go to the text document and click the both buttons simultaneously for copying the details from terminal to text document.

this is what worked for me ..im on ubuntu 16.04 LTS

I found the solution here

Problem

Copy Paste text from PuTTY to Another Application on Ubuntu not working

solution

Select the text you want to copy on the screen and leave as it is. This will copy the text to PuTTY clipboard.

pasting to other application:

Go to the other application and press the middle button of the mouse. If your mouse only has two buttons, then press both left and right buttons simultaneously, it will paste the text on the other application. However, if you try to use CTRL + V , it will paste the content which is present in the default clipboard.

This worked for me on Fedora