I am having the exact same issue. Client told me their twitter feed is no longer appearing but when I am checking the widget code its exactly as it is within their twitter account and if I check the html on the page its also right there.
The site is: http://www.tanukidata.com/
Inside of developer console its throing an error saying:
Uncaught Error: widgetId is a required parameter
This is what I have for the code:
<a class="twitter-timeline" href="https://twitter.com/tanukidata" data-widget-id="261410699086004224">Tweets by @tanukidata</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>