social icon not readable

It’s because you have done customization of the social login icons yourself. If you want to customize the icons, you can install the add-on https://www.heateor.com/social-login-buttons/ or drop an email at support[at]heateor[dot]com

nope i did not customize itself, how can i go for default icons?

By default, icons look like as shown at the demo page https://super-socializer-wordpress.heateor.com/