As-salamu `Alaykum warahmatullah wabarakatuh (May Allah's Peace, Mercy, and Blessings be upon you!).
Dear sheikh, I have been married for seven months but until now I could not have sexual intercourse with my wife despite my frequent tries which exceeded three times, but I could not.
My wife does not refuse me, but responds to me effectively.
What is your advice? May Allah reward you the best!
All praise be to Allah and peace be upon the Messenger of Allah, upon his family, his Companions, and those who follow him righteously.
My advice to you is to treat yourself psychologically and spiritually in the same time. Recite the Ayahs of Ruqyah (reciting Qur'an and saying supplications over the sick seeking healing) because it may happen because of devils, Jinn, sorcery, or something else, and treating all these is easy with the will of Allah through Ruqyah. Scholars have mentioned that the one who cannot have sexual intercourse with his wife may take seven leaves from green lote tree and grind them in a pot and pour some water over [enough to use in bathing] and recite over them:
1- Surat of Al Fatihah.
2- Ayat-ul-Kursy (the Qur'anic Verse of Allah's Chair, Surah Al-Baqarah, 2:255), which reads: "Allâh! Lâ ilâha illa Huwa (none has the right to be worshipped but He), Al-Hayyul-Qayyuum (the Ever Living, the One Who sustains and protects all that exists). Neither slumber nor sleep overtakes Him. To Him belongs whatever is in the heavens and whatever is on the earth. Who is he that can intercede with Him except with His Permission? He knows what happens to them (His creatures) in this world, and what will happen to them in the Hereafter. And they will never compass anything of His Knowledge except that which He wills. His Kursî extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And He is the Most High, the Most Great." [Surat Al Baqarah: 255].
3- Ayahs from Surat Al A`raf, which read: "[Fir'aun (Pharaoh)] said: If you have come with a sign, show it forth, if you are one of those who tell the truth. * So [Mûsâ (Moses)] threw his stick, and behold, it was a serpent, manifest. * And he drew out his hand, and behold, it was white to all beholders! * The chiefs of the people of Fir'aun (Pharaoh) said: "This is indeed a well-versed sorcerer; * He wants to get you out of your land, so what do you advise? * They said: Put him off and his brother (for a while), and send callers to the cities; * That they bring to you all well-versed sorcerers. * And so the sorcerers came to Fir'aun (Pharaoh). They said: Indeed there will be a (good) reward for us if we are the victors. * He said: Yes, and moreover you will (in that case) be of the nearest (to me). * They said: O Mûsâ (Moses)! Either you throw (first), or shall we have the (first) throw? * He [Mûsâ (Moses)] said: "Throw you (first)." So when they threw, they bewitched the eyes of the people, and struck terror into them, and they displayed a great magic. * And We revealed to Mûsâ (Moses) (saying): Throw your stick, and behold! It swallowed up straight away all the falsehood which they showed. * Thus truth was confirmed, and all that they did was made of no effect. * So they were defeated there and returned disgraced. * And the sorcerers fell down prostrate. * Saying: We believe in the Lord of the 'Alamîn (mankind, jinn and all that exists). * The Lord of Mûsâ (Moses) and Hârûn (Aaron)." [Surat Al A`raf: 106 - 122].
4- Ayahs from Surat Yunus, which read: "And Fir'aun (Pharaoh) said: Bring me every well-versed sorcerer. * And when the sorcerers came, Mûsâ (Moses) said to them: Cast down what you want to cast! * Then when they had cast down, Mûsâ (Moses) said: "What you have brought is sorcery; Allâh will surely make it of no effect. Verily, Allâh does not set right the work of Al-Mufsidûn (the evil-doers, corrupters). * And Allâh will establish and make apparent the truth by His Words, however much the Mujrimûn (criminals, disbelievers, polytheists, sinners) may hate (it)." [Surat Yunus: 79 - 82].
5- Ayahs from Surat Taha, which read: "They said: O Mûsâ (Moses)! Either you throw first or we be the first to throw? * [Mûsâ (Moses)] said: Nay, throw you (first)! Then behold! their ropes and their sticks, by their magic, appeared to him as though they moved fast. * So Mûsâ (Moses) conceived fear in himself. * We (Allâh) said: Fear not! Surely, you will have the upper hand. * And throw that which is in your right hand! It will swallow up that which they have made. That which they have made is only a magician's trick, and the magician will never be successful, to whatever amount (of skill) he may attain." [Surat Taha: 65 - 69].
6- Surat Al Kafirun.
7- Surat Al Ikhlas and Al Mu`awidhatayn: Surat Al Falaq and Surat An-Nas (thrice).
8- Reciting some supplications, such as:"O Allah! The Lord of Mankind, take away the disease, You are the Healer, None brings about healing but You; a cure that leaves no disease." (thrice) and recite:"By the name of Allah, I protect you against everything that may harm you and safeguard you from every evil (that may harm you) and from an envious eye. Allah would cure you, by the name of Allah I protect you." (thrice)
Moreover, you should keep obeying Allah (may He be Exalted), keep away from disobeying Him, and keep reciting the Qur'an and Adhkar, such as Adhkar that were reported from the Prophet (peace be upon him) in the morning, in the evening, at eating and drinking, after finishing, upon going out and going in the house, upon sleeping and waking up.
Recite the Qur'an frequently with contemplation, especially Surat Qaf, Ad-Dukhan, Yasin, As-Safat because they are tested in all cases, and in the same time see a psychiatrist.