Where was Imam Raza when Imam Musa Kazim(as) was in prison for more than 14 years and then his dead body was kept on bridge? Why Imam Raza didnt come to meet his father? Why he didn't do anything to get him released from prison and why he wasnt present when 7th Imam died? Why for 14 years Imam Raza didnt look for his father?

It is not the case as you are thinking. As I said that first of all we should remove this very common thinking that our Imams were living their life based on miracle. Allah (swt) gave miracle to Prophets to prove their Prophecy and authenticity as they are a divine leader and in the same way Allah gave power to Imams also to prove their Imamate and divine leadership. So it’s not true that they were not having a normal life. No, most of their life was normal like other Human being they were eating, sleeping, sometimes becoming sick and doing marriages having family life ect.

On the other hand if you know that this world is based on one philosophy that everything in this world works according to “ cause and effect” therefore it’s not that if a person is good and pious drinks poison, he will not get harm and if a bad person drinks normal water he will get harmed. No don’t think like that. If Hidayat (guidance) was supposed to be an act of miracle then why Allah (swt) has created us in human form and why He gave us Aql( intellect) to differentiate what is bad and what is good. Allah (swt) is capable to do what He wishes then why He doesn’t he make all human good. If this was the case then there will be a big question that why He has created us in this form while there are two other creation of Him already exist who can’t do what they wish ( angels they can’t do mistakes because they don’t have any Desire and Animal can’t any logical acts as they have only Desire but not an intellect) but the same time it’s only human being who has both and so with this power of Desire and Intellect he can decide and choose with his FREE WILL what is good and what is bad. On top of that Allah has sent 124000 Prophets and 12 Imams to guide human where their Aql can’t work or can’t reply therefore they would have no excuse for their mistakes and sins on the Day of Judgement.

Now if you read history Haroon ar Rashid (an Abbaside King) was most powerful King every in Muslims history even more powerful that Muawia and Yazid too. The other side Imam’s lives were not based on miracle yes whenever it was required to people and King’s event their divine power they showed that they are not an ordinary person as you assume but rest of the time life was normal.

Also 7th Imam wasn’t in prison for 14 years CONTINUOUSLY but from time to time the Imams were brought in from Madina, kept in Baghdad either on house arrest or inside prisons under the most difficult of conditions. But it was the Imams great Divine Characters that managed to keep them going in the most severe of conditions.
Now how it was possible for Imam Reza to bring Imam Musa Kazim ( as) from prison?

Also most interesting when Imam Musa Kazim ( a.s) was alive, he is Imam e Masoom and divine Leader of Allah on Earth and Hujjat (proof) of Allah. You know what it means? It means 7th Imam was the Most Powerful most knowledgable and most pious human being on the Earth then why he could not release himself from imprisonments of Haroon while he could have this power? Ofcourse if Imam(a.s) would wish he could release him and history shows he did many times but not always. Our Imams life was based on Allah’s not what people are thinking or people will think.

Last time when Imam Musa Al Kazim (a.s) was brought to Baghdad he was sent to different prisons at last nearby on of the Baghdad’s prison under the custody of Sindi bin Shahik (one of cruel and evil jailers of Haroon Rasheed may Allah curse them) Imam(a.s) left this material world. Therefore Imam Reza (a.s) was in Madina at that time but when the news of his Martyrdom reached to the Sulaiman bin Abi Jaffer ( who was uncle of Haroon) and one of the Shia of 7th Imam (a.s), he threw his Ammama on the ground and opened his chest and reached to Imam’s holy body and commanded his people that any how you dispersed the people of Imam then took the responsibility of Ghusl but according to rewayat of Bihar Al Anwar Allama Majlisy and Shiekh Sadooq Imam Reza (a.s) appeared by Miracle and Sulaiman bin Jaffer saw him then Imam has performed Ghusl, Kafan and Namaz while others were looking as if Haroon’s people were giving Ghusl to Imam while Imam Reza was doing it.
بحار الانوار، ج 48، ص 225، ح 26 از عیون.
Reference: Bihar al Anwar, Vol: 48, page 25.

Why Imam didn’t come at the time of His death?
Yes 8th Imam (a.s) came and it’s Allah’s arrangement that the Knowledge if Imamate has to be transferred but as for as other affairs concern e.g his death and why 8th Imam didn’t to anything to bring Imam (a.s) from the prison at last moment these all are the part of the system of divine arrangements and most importantly these are having lessons and messages and reason to show the hidden faces of tyrant rulers of that time. They’re many things we can discuss at this moment.