Add Random Posts with Thumbnails for blogger

this widget might help you.The Random Posts Widget will show random posts you have added to your blog. this widget is that it is loading pretty fast and shows thumbnails of your posts too, along with the comments link.

Random Posts widget is an awesome widget for your Blogger Blog.Most important feature of this widget is it lets your Blog visitors to surf more blog posts in your blog.Surely it increases your Blog's internal links that lets your blog higher traffic.
How To Install

1. Click on the 'Layout' tab
2. Click on the "Add a Gadget".
3. Click on the " HTML/JavaScript".
4. Paste in the code.

<style type="text/css">
#random-posts img{float:left;margin-right:10px;border:1px solid #999;background:#FFF;width:36px;height:36px;padding:3px}
</style>

<ul id='random-posts'>
<script type='text/javaScript'>
var rdp_numposts=6;
var rdp_snippet_length=150;
var rdp_info='yes';
var rdp_comment='Comments';
var rdp_disable='Comments Disabled';
var rdp_current=[];var rdp_total_posts=0;var rdp_current=new Array(rdp_numposts);function totalposts(json){rdp_total_posts=json.feed.openSearch$totalResults.$t}document.write('<script type=\"text/javascript\" src=\"/feeds/posts/default?alt=json-in-script&max-results=0&callback=totalposts\"><\/script>');function getvalue(){for(var i=0;i<rdp_numposts;i++){var found=false;var rndValue=get_random();for(var j=0;j<rdp_current.length;j++){if(rdp_current[j]==rndValue){found=true;break}};if(found){i--}else{rdp_current[i]=rndValue}}};function get_random(){var ranNum=1+Math.round(Math.random()*(rdp_total_posts-1));return ranNum};
</script>
<script type='text/javaScript'>
function random_posts(json){for(var i=0;i<rdp_numposts;i++){var entry=json.feed.entry[i];var rdp_posttitle=entry.title.$t;if('content'in entry){var rdp_get_snippet=entry.content.$t}else{if('summary'in entry){var rdp_get_snippet=entry.summary.$t}else{var rdp_get_snippet="";}};rdp_get_snippet=rdp_get_snippet.replace(/<[^>]*>/g,"");if(rdp_get_snippet.length<rdp_snippet_length){var rdp_snippet=rdp_get_snippet}else{rdp_get_snippet=rdp_get_snippet.substring(0,rdp_snippet_length);var space=rdp_get_snippet.lastIndexOf(" ");rdp_snippet=rdp_get_snippet.substring(0,space)+"&#133;";};for(var j=0;j<entry.link.length;j++){if('thr$total'in entry){var rdp_commentsNum=entry.thr$total.$t+' '+rdp_comment}else{rdp_commentsNum=rdp_disable};if(entry.link[j].rel=='alternate'){var rdp_posturl=entry.link[j].href;var rdp_postdate=entry.published.$t;if('media$thumbnail'in entry){var rdp_thumb=entry.media$thumbnail.url}else{rdp_thumb="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiB9TCUKIgUUHnBc0f864j-9qStZggr8uUWpMvb3ZStBaz35O5Z63dRFA30LcNKRdBWDCwZYuFwgo36GreBrSeFcuiN3ZbAL2Ks2yA6QzQbNgNtpYHQ-QBlTgFIg5c9Pi8vwDiRCXOIVEs/s1600/default.jpg"}}};document.write('<li>');document.write('<img alt="'+rdp_posttitle+'" src="'+rdp_thumb+'"/>');document.write('<div><a href="'+rdp_posturl+'" rel="nofollow" title="'+rdp_snippet+'">'+rdp_posttitle+'</a></div>');if(rdp_info=='yes'){document.write('<span>'+rdp_postdate.substring(8,10)+'/'+rdp_postdate.substring(5,7)+'/'+rdp_postdate.substring(0,4)+' - '+rdp_commentsNum)+'</span>'}document.write('<div style="clear:both"></div></li>')}};getvalue();for(var i=0;i<rdp_numposts;i++){document.write('<script type=\"text/javascript\" src=\"/feeds/posts/default?alt=json-in-script&start-index='+rdp_current[i]+'&max-results=1&callback=random_posts\"><\/script>')};
</script>
</ul>

Note: Replace no. 6 with the number of posts you want to be show.