The verb "to block" is transitive. It expects a semantic patient. In the active voice, that patient is supplied by a direct object.
Congestion blocks my nose.
Here, the subject "congestion" represents the semantic agent, the verb "blocks" represents the action in the active voice, present tense and indefinite aspect, and the direct object "my nose" represents the semantic patient.
Congestion has blocked my nose.
Here, the verb is still in the active voice, "congestion" is still the agent, and "my nose" is still the patient. This form of the verb is a perfect aspect form.
My nose is blocked.
Here, the verb is in the passive voice. There is no agent in the sentence, and no agent is required. The subject represents the patient.
* My nose has blocked.
Here, we have a problem. The transitive verb is in the active voice, but the required patient is missing. We know what does the blocking, but we don't know what gets blocked. Perhaps my nose is large enough to block your view, or to block your way. This sentence might make sense in a different context, but it does not mean what you want to say.
My nose has been blocked.
Here, we have a solution. This form of the verb is in both the passive voice and the perfect aspect. The subject "my nose" is once again the patient, as it should be in this context.
Unlike "my nose is blocked", "my nose has been blocked" makes sense with durations. It expresses a state that exists for some time. My nose has been blocked for several hours. My nose has been blocked since last week. My nose has been blocked before, and I'm sure it will be blocked again.