This is a common question. If you are using a DSL service, every time you turn on your computer your IP address is changed. But this does not mean that you are not still banned on eBay, on a forum or on-site you got banned before.
Why is that?
The answer is very simple: you are still on the same subnet. Meaning that your new IP address is not very different from the one that you got banned with. For example, you got banned with 18.104.22.168 and your new IP address is 22.214.171.124. Forums or sites like eBay don’t ban only the exact IP, but the entire subnet.
What should you do?
Firstly, you could change your ISP (Internet Service Provider), create a new account and make sure you set up all new account information and do not link any old account information.
Secondly, you can try changing your IP address. You can find a lot of articles on this blog on how to do it.
If you need a US IP address you can read this post. Also, I recommend a product that I have recently discovered some good VPN services and that offers high quality US IPs. It seems to be designed especially for these cases. I will later write a post about this product.