If someone asks where are guardian angels in the Bible, the clearest answer is found in the gospel.
In the gospel of Matthew we read "Beware that you don't despise a single one of these little ones. For I tell you that in heaven their angels are always in the presence of my heavenly Father.*
The Church continues to teach not just a belief in angels in general but in guardian angels specifically, purely spiritual beings whose role it is to watch over us.
I would simply remind you of the simple prayer:
Angel of God, My Guardian Dear to whom God's love commits me here.
Ever this day be at my side to light and guard and rule and guide. Amen.