My heart was dead for a longtime too. While the shaytaan kept laughing i decided enough is enough! Picked myself up and made changes. Started of small: Pray on time, read duas when free, read tasbeeh, give to charity, go the extra mile to help people, pray for repentence( not just for me but the whole of the ummah), abstain from sin (this is no small change and deffo not the easiest but i gave it my all) started caring about my health more and the list goes on. My heart was pure black before all this, but alhumdulilah day by day it was being filled with nuur. After 2 weeks of abstaining from sin and praying on time and doing all sorts of good deeds, my heart was revived! Yes revived! Something which i thought was impossible. From there i increased my good deeds, increased time spent on the prayer mat and tried to increase my knowledge. Each day of those 2 weeks i read tasbeeh of "astagfirullah" and prayed 2 raqa namaz for forgiveness. By the 2 weeks were up, i honestly felt forgiven by Allah - the most gracious the most forgiving.
Sorry for the long paragraph but i could really relate to you here so i guess its worth it if u can take in even one thing.
Keep fighting and stay strong. Know Allah's love is stronger than the love of 10 mothers! Keep asking for repentence and keep praying.
ps: the first 2 weeks i kept a tally chart to help push me a bit in not sinning and giving me some motivation. Everyday you keep away from sin or everyday u prayed 5 times just mark down a tally or a line.
i will keep you in my prayers.
All the best.