A lot of people, myself included, have at one time felt like we sin so much that we cannot approach God in prayer. "I'm too dirty to approach God right now" is one of the most common phrases I've heard and while we think we're the only ones failing God while everyone seems to be doing much better, trust me, we're all in the same boat of sinners. Interestingly but not surprisingly, God clearly knows everything there is to know about His creation and has prepared for these moments of weakness that we go through in His word! Hebrews 4:16 says "Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need." This verse is just so reassuring especially in bad seasons when we feel we aren't 'good enough' to come to God for comfort, confession and mercy! In fact in Mark 2:17 Jesus Himself said that He has come for the sick (that means us). I heard this phrase once that really stuck with me - just because we are born again doesn't mean we become sinless, we just sin less. What this means is that we can never truly get rid of our sinful nature while we're still in the flesh in this world, once Jesus abides in us, we become a new creation which gradually sins less not because we are told not sin but because the love of Jesus convicts us, pricks our heart every time we fall into sin and gives us the zeal to change for God's glory. If parables resonate with you I would strongly suggest reading Luke 15:11-32 about the prodigal son.
Blessings!