You are able to login at certain Dark Web markets only with an alternative link, that determines the following : new vendees and vendors are not allowed to register before they will gtab an URLs from an already registered user.
Those can be found at http://deeponionmarkets.com/, it posts fresh urls to concerning Deep Web markets. You should follow these URLs to get access to the sites.
Wherever there are some troubles with an access,for example, links won’t work, you may lie in wait and check for Deep Web markets URL. Keep trying, as some of the marketplaces may stop and launch signing up frequently, depending on server load.