Can you post in other bars? If so, so be it. The administrator put a ban on you.

You don't have to worry about that. Generally, it will be unsealed automatically in 15 days at the longest. Just wait.

If you can't send it in other bars, then your account has been banned by Baidu. This is generally limited by time. You can appeal. You can directly search Baidu Post Bar in Baidu to make a complaint.