No, I didn't back it up. When I did this, quite a few years ago, I wasn't sure what I was doing and was pleasantly surprised when I was able to get an image. I don't remember how I did it and could have sworn that GB had info on how to add an avatar to your profile. Otherwise, I'm not sure how I figured out how to do it. Did we used to have information on here about that?
If I am understanding what you guys are saying, my avatar was from a URL that removed the image, so my link no longer works? I got a new computer a couple of years ago and the original image was on the old one. I don't know anything about photobucket or imageshack. I have been looking for a new avatar and would like to know what size the image should be.
Not quite. The URL is the address to the site where something is stored or accessed. In your case, the URL you used for your avatar was the address to the site where the avatar was stored. If you didn't change your avatar here on GB, in your profile, then something has happened to the URL so GB can no longer access that site. This could be caused by several things, notably because the site shut down. Another cause could be because the site name changed, or it moved. The point being, GB can no longer find the site storing your avatar.
What you could do until you find something you like is to go My Place, top of page, Edit Profile and scroll to the bottom of the screen and use one of GB's own avatars.