User Avatars in the comment section generally stop showing after a WordPress update, or when you change some settings or install a new plugin. There can be any number of reasons for it. Lets discuss each of them one by one.
Addition of a New Plugin
Did you recently install any new plugin? Check all the new plugins you installed. One of them may be conflicting with the code responsible for showing the comments.
WordPress blogs support Gravatar by default. There can be additions to Gravatar, like “Gravatar Hover Cards” enabled by Jetpack. See if Disabling that helps.
After WordPress update?
Did the comments stop showing avatars after a recent WordPress update, or you didn’t notice at the time of update and suddenly they do not work. Then you need to update a small piece of code in one of your files. The code you need to search for isget_avatar . It is a function being called by one of the files responsible for the comments section.
First go to Dashboard > Appearance > Editor
If you are using a theme from rohitink.com, then this code should be available in the template-tags.php file, inside the inc folder. Other possible files where you can find this code is comments.php, functions.php or some other file too.
Once you have located the code. It should look something like this:
get_avatar( $comment, array(150,150) )
All you have to do is replace it with
get_avatar( $comment, 150 )
Save the file. Clear any cache, if you have a plugin enabled. Refresh your site. And the problem should be solved now. If its still not solved, try commenting below with your exact issue and I will try to help.