Is there any verse in the accepted Books by Jews and Protestants says that we can gain forgiveness of sins by alms ?
I don't know about alms, but the new covenant appears to follow the old
re:confession and repentance.
“He who covers his sins will not prosper,
but whoever confesses and forsakes them will have mercy.”
1 John 1:7-2:1
"But IF we walk in the light as He is in the light, we have fellowship with one another,
and the blood of Jesus Christ His Son cleanses us from all sin.
If we say that we have no sin, we deceive ourselves, and the truth is not in us.
IF we confess (and repent of) our sins, He is faithful and just to
forgive us our sins and to cleanse us from all unrighteousness.
If we say that we have not sinned, we make Him a liar, and His word is not in us.
My little children, these things I write to you, so that you may not sin.
And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous."