If you want to replace paragraph breaks (newlines) with a comma in Notepad++, follow these steps:

1. Open the file in Notepad++.

2. Press Ctrl + H to open the "Find and Replace" dialog.

3. In the Find what field, enter \r\n (for Windows) or \n (for other systems).

4. In the Replace with field, type..

5. Select Match using Regular Expression at the bottom.

6. Click Replace All.