Fix whatever is wrong with your Gmail account, then use that to access your eBay account.
Or else use the "Need help signing in?" link on the page where you enter your eBay password after entering your username. If you follow the link to reset your password, on that page you should see a contact link specifically for users that are unable to sign in to eBay. You will need to prove that you are the original account holder before you will be able to update any contact info.
