Can God turn our failure into success?

Psalm 51 NIV84

1 For the director of music. A psalm of David. When the prophet Nathan came to him after David had committed adultery with Bathsheba.
1 Have mercy on me, O God, according to your unfailing love; according to your great compassion blot out my transgressions.
...
10 Create in me a pure heart, O God, and renew a steadfast spirit within me.
11 Do not cast me from your presence or take your Holy Spirit from me.
12 Restore to me the joy of your salvation and grant me a willing spirit, to sustain me.
13 Then I will teach transgressors your ways, and sinners will turn back to you.
14 Save me from bloodguilt, O God, the God who saves me, and my tongue will sing of your righteousness.
15 O Lord, open my lips, and my mouth will declare your praise.
16 You do not delight in sacrifice, or I would bring it; you do not take pleasure in burnt offerings.
17 The sacrifices of God are a broken spirit; a broken and contrite heart, O God, you will not despise.

I love Psalm 51:17.  I mess up regularly.  And when I have messed up bad, and the excuses don't mean a thing, I have this cry of David to give me the comfort I am desperately looking for.  If I "own" my evil action, and wish I had never done it, and I am committed to never doing it again, Our Father in Heaven will "blot out my transgressions".  Why would He do that?  Because of all the good things I've done? or all the good things I promise to do?

No.

He forgives me because He is my Father and He loves me.  (And He loves you just as much).  And He has the right to forgive us because He suffered and died to pay the price for our sins.

But what does Our Father do when I have been forgiven and commit the exact same sin again, and again, and again?!  Matthew records Jesus:

Then Peter came to [Jesus] and said, “Lord, how often shall my brother sin against me, and I forgive him? Up to seven times?”
Jesus said to him, “I do not say to you, up to seven times, but up to seventy times seven.

Matthew 18:21-22 NKJV

If God tells us to forgive others that many times, how will He treat us?  Our Father has limitless compassion on us His children.  If He endured torture and death for us when we were His enemies, what will He withhold now that we are His friends?  Or, as the Apostle Paul wrote:

But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us. Much more then, having now been justified by His blood, we shall be saved from wrath through Him. For if when we were enemies we were reconciled to God through the death of His Son, much more, having been reconciled, we shall be saved by His life. And not only that, but we also rejoice in God through our Lord Jesus Christ, through whom we have now received the reconciliation.

Romans 5:8-11 NKJV

If you genuinely turn away from sin each time, each time God will forgive you.  A word of warning however.   Forgiveness does not mean that there are no consequences to sin.  I rejected God when I was nearly twenty years old. And I continued to reject Him for the next ten years.

And at 54 years old, though forgiven, I still have the mental illness that was the consequence of that first decision to reject God.

But God will make even the consequences of our sin work together for our good.  The Apostle Paul writes:

And we know that all things work together for good to those who love God, to those who are the called according to His purpose. 

Romans 8:28 NKJV

In my case, my consequence of mental illness has given me insight and credibility to help others who are experiencing mental illness and/or to help their loved ones understand what mental illness is like.  Whatever mistakes you have made, if you turn from it, God can use it for good.  And He can make using that mistake an opportunity to help others... And a joy!

Why don't you ask Him to do that for you right now?