Question about replacing \r\n with <br>

I can't find a way to replace \r\n codes with <br> in a text file. I'm reading a text file that was prepared with windows notepad The hex code shows OD OA for CR/LF as I expect. I'd like to replace the OD/LF with <br>s. I spent hours trying every User Notes in the PHP Manual for this simple operation. e.g., $txt= preg_replace("\r\n", "<br>", $words); and this version $txt = preg_replace("/(\015\012)|(\015)|(\012)/","<br />", $txt); I can substitute other characters and dec equivalents and the substations just won't work for \r\n [or just \r or just \n] or "\015" or "\15". And, I've tried using "10" and "010" and "13" and "013". And nl2br doesn't work either. Can anyone help? Thanks........