If you cannot enter the MUT auction house, most likely your account got actioned (i.e. banned or suspended). There are various reasons why your account may be banned or suspended. The forums team neither can directly help you with account related issues nor do the community managers have access to your account (i.e. seeing why your account got actioned) due to safety reasons.
Please see the accepted solution below for further information about bans and suspensions and how to contact the ToS team (Terms of Service) if you want to dispute your ban/suspension. They are the only ones who are responsible for bans and suspensions and who know the details why your account got actioned.
By the way: if your account got banned/suspended, independent of whether the ban/suspension was justified or not, it would be a good point in time to read the rules of the game (again) in order to avoid facing a ban or suspension in the future again. You will find the rules here.
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Positive Play - Feel the emotions, but be aware what they are telling you!
Joy: you like it! Anger: you don't like it! Frustration: you don't like it but cannot do
anything against it! Aggression: you don't like it and want to break something.
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Tell everybody (@joy), give constructive feedback (@anger),
ask for help (frustration), and have a break (@aggression)!
I try to help out other players, but I'm not an EA employee
