In case you have a file which contains “escaped” new lines (\n), like this:
and you want to replace the escaped new line sequences with actual new line characters, you can easily accomplish this task using Notepad++.
First load your file (or just copy paste the text) in Notepad++.
Then select Search → Replace from the menu, or hit Ctrl-H. The Replace dialog will show up. Therein make sure that you fill out the following values; Find what: \\n (yes, two back-slashes), Replace with: \n (yes, just one back-slash), and the most important, make sure you select the Extended (\n, \r, \t, \0, \x, …) radio button. Your Replace dialog must look like this:
Click the Replace All button, and all escaped new line sequences will be replaced with new line characters:
I hope this helped!