Be frequent in the recitation of the Qur’an, for it softens the hearts — as Allah the Most High says:

للَّهُ نَزَّلَ أَحۡسَنَ ٱلۡحَدِيثِ كِتَٰبًا مُّتَشَٰبِهًا مَّثَانِىَ تَقۡشَعِرُّ مِنۡهُ جُلُودُ ٱلَّذِينَ يَخۡشَوۡنَ رَبَّهُمۡ ثُمَّ تَلِينُ جُلُودُهُمۡ وَقُلُوبُهُمۡ إِلَىٰ ذِكۡرِ ٱللَّهِۚ ذَٰلِكَ هُدَى ٱللَّهِ يَهۡدِى بِهِۦ مَن يَشَآءُۚ وَمَن يُضۡلِلِ ٱللَّهُ فَمَا لَهُۥ مِنۡ هَادٍ

Allah has sent down the best statement, a Book (this Quran), its parts resembling each other in goodness and truth, oft-repeated. The skins of those who fear their Lord shiver from it (when they recite it or hear it). Then their skin and their heart soften to the remembrance of Allah. That is the guidance of Allah. He Guides therewith whom He pleases and whomever Allah sends astray, for him there is no guide. Az-Zumar 39:23

The Quran softens the heart because it is the speech of the Lord of all that exists. So, if you train yourself — and your tongue — to recite the Quran with contemplation and presence of heart, your heart will indeed become soft.

أَلَمۡ يَأۡنِ لِلَّذِينَ ءَامَنُوٓاْ أَن تَخۡشَعَ قُلُوبُهُمۡ لِذِكۡرِ ٱللَّهِ وَمَا نَزَلَ مِنَ ٱلۡحَقِّ وَلَا يَكُونُواْ كَٱلَّذِينَ أُوتُواْ ٱلۡكِتَٰبَ مِن قَبۡلُ فَطَالَ عَلَيۡهِمُ ٱلۡأَمَدُ فَقَسَتۡ قُلُوبُهُمْۖ وَكَثِيرٌ مِّنۡهُمۡ فَٰسِقُونَ

Has not the time come for the hearts of those who believe (in the Oneness of Allah) to be affected by Allah’s Reminder (this Quran), and that which has been revealed of the truth, lest they become as those who received the Scripture [the Taurat (Torah) and the Injeel (Gospel)] before (i.e. Jews and Christians), and the term was prolonged for them and so their hearts were hardened? And many of them were Fasiqun (rebellious, disobedient to Allah). Al-Hadid 57:16

In the following verse, Allah (Glorified and Exalted be He) says:

ٱعۡلَمُوٓاْ أَنَّ ٱللَّهَ يُحۡىِ ٱلۡأَرۡضَ بَعۡدَ مَوۡتِهَاۚ قَدۡ بَيَّنَّا لَكُمُ ٱلۡأٓيَٰتِ لَعَلَّكُمۡ تَعۡقِلُونَ

Know that Allah gives life to the earth after its death! Indeed We have made clear the Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) to you, if you but understand. Al-Hadid 57:17

The dead heart is revived through the remembrance of Allah. Do not despair. Treat your heart with the remembrance of Allah, and — by Allah’s permission — it will come back to life.

Sharh al-Mandhumah al-Aadab ash-Shari’yyah pgs. 935-936