Sufyan ibn ‘Uyaynah said “Let none of you think that his Du’aa will go unanswered because of the sins that he knows of himself.
Indeed, Allah responded to the Du’aa of the worst amongst His creation; Iblees (Shaitan, the cursed one), when he said; ‘O My Lord! Give me respite until the Day of Judgement!’ He (Allah SWT) replied, ‘Then you are of those who have been reprieved.‘ (Surah al-Hijr 36-37).
So if the Du’aa of Iblees’ can be accepted, then surely the Du’aa of a sinner has more right than the devil himself!” And surely your Lord is never unjust…
May Allah accept our Du’aas and grant us the ability to continuously seek His forgiveness (through sincere repentance)… Ameen.
Do not despair of the infinite mercy of Allah
Say: My servants who have acted extravagantly against themselves still do not despair of Allah’s mercy. Allah forgives all offences; He is the Forgiving, the Merciful (Az-Zumar 39/53).*
Ibrâhîm ibn Adham (d.160H) – rahimahullâh – said, when he was asked about the verse: “Call upon Me and I will respond to you.” [Sûrah Ghâfir 40:60] They said: We call upon Allâh, but He does not respond to us. So he said:
“You know Allâh; yet you do not obey Him.
You recite the Qur’ân; yet you do not act according to it.
You know Shaytân; yet you continue agreeing with him.
You claim to love Allâh’s Messenger ‘alayhis-salâm; yet you abandon his Sunnah (guidance and way).
You claim to love Paradise, yet you do not work for it.
You claim to fear the Fire; yet you do not stop sinning.
You say, Indeed death is true; yet you have not prepared for it.
You busy yourselves with the faults of others; yet you do not look at your own faults.
You eat the sustenance that Allâh provides for you; yet you are not grateful to Him.
And you bury your dead; yet you have not heeded its lesson.” 
 Al-Hâfidh Ibn Rajab related it in al-Khushû’ fis-Salâh (p.62).