Praise be to Allah.
If the matter is as you describe, that you reached Jeddah without ihram because you intended to go to Madinah first, then enter ihram from there, but the authorities prevented you from going to Madinah, so you entered ihram from Jeddah, then there is no blame on you, because when you first went to Jeddah, you were not intending to do Hajj, so you were not required to enter ihram from the miqaat when you passed by it; rather you intended to do Hajj when you travelled from Madinah, in which case you would have had to enter ihram from its miqaat (Dhu’l-Hulayfah).
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked: A man came from Jeddah and did not enter ihram; first he went to al-Madinah al-Munawwarah to visit the Prophet’s Mosque, then he entered ihram from the miqaat of the people of Madinah; is this valid?
He replied: There is nothing wrong with that. That is, if a person comes from his country, intending to go to Madinah first, and he halts in Jeddah, then he travels from Jeddah to Madinah, then he comes back from Madinah having entered ihram from the miqaat of the people of Madinah, there is nothing wrong with that. End quote from Liqa’ al-Baab al-Maftooh (121/29)
As it was not possible to travel to Madinah, and then you decided to do Hajj, then you could enter ihram from where you were, i.e., in Jeddah, and this is what you did, praise be to Allah, so you do not have to do anything further.
We ask Allah to accept acts of worship from us and from you.
And Allah knows best.