Create a text file under /content/dam/abc called dam.txt, Usually the txt file gets downloaded on author instance, Think of a way to display its content on the browser instead of download.

@jhansi_123 I believe you have created custom component to render txt content - In that case please follow below steps.

• Create Sling Model
• Create OSGi Service
• Refer/ Call to that OSGi service through Sling Model 
• Render that content in HTL with the help of Sling Model

Please refer below sample code which you may need to read txt from JCR. 

File should have an nt:file node, which has a jcr:content node with jcr:data property.
You can read the xml from jcr:data i.e: jcrContent.getProperty("jcr:data").getBinary().getStream();/

InputStream is = jcrContent.getProperty("jcr:data").getBinary()
                    .getStream();

            BufferedInputStream bis = new BufferedInputStream(is);
            ByteArrayOutputStream buf = new ByteArrayOutputStream();
            int resultNumber = bis.read();
            while (resultNumber != -1) {
                byte b = (byte) resultNumber;
                buf.write(b);
                resultNumber = bis.read();
            }