If you have never logged into Lockerz before, but you see your pictures hosted here and tied to your Twitter name - this just means that you used a third party Twitter client, such as Echofon or Ubersocial to upload photos and tweet.
When you are uploading photos through these third party services, it's important to keep in mind that there are different photo service providers to choose from, and it's up to you to make the decision of which would better suit you.
How do I gain access to these photos?
To gain access to these photos, you must create a Lockerz account and connect it with Twitter. You can do this easily by viewing your photo page and clicking "Is this your photo?"