I assume you have gone to your Edit My Profile section and then to the Change Avatar section.
It looks like the problem is that you are using the Gravatar method of uploading your avatar and have put something invalid in the Gravatar input box. When you do that it defaults to the Gravatar company icon (which is the blue and white sideways "G" that currently is appearing as your icon).
You need to either put a valid entry into the Gravatar input box, or, if you are instead trying to upload the image from your hard drive or from a link to an online photo then you need to delete anything you have put into the Gravatar input box.
Clear as mud?