Assuming these are text files (since you are using notepad++) and that you are on Windows, you could fashion a simple batch script to concatenate them together.
For example, in the directory with all the text files, execute the following:
for %f in (*.txt) do type "%f" >> combined.txt
This will merge all files matching *.txt into one file called combined.txt.
For more information:
http://www.howtogeek.com/howto/keyboard-ninja/keyboard-ninja-concatenate-multiple-text-files-in-windows/