Taking money that was kept by someone as amaanat unjustly

Q: I would appreciate your guidance on the following two queries/issues.

Query/Issue #1: I will refer to two individuals as “Person A” and “Person B”. Person A had 2 packets containing money. These packets were given to Person B by mistake. The same day, Person A had informed Person B of the mistake and requested that these parcels be returned. Person A had a full account and record of the money, who it belonged to, date and amounts. Unfortunately Person B has now taken “ownership” of this money parcels unjustly and does not want to acknowledge nor accept Person A version and has discarded all these records that was with the parcels. Person A has taken an oath that the money parcels belongs to Person A. What is the Sharia ruling (Islamic ruling) on who has the right to these money parcels.

Query/Issue #2: If some money was left in trust with an individual, and such money was taken unjustly and without neglect by the responsible individual, is this individual liable for returning and/or executing on the instruction of such money?

Making Towbah

Q: I am in a lot of trouble. My son was 21 years old. He is unmarried and he did a big mistake with a foreign girl. My son did sex for the first time. It is a big gunnah. Please give me a solution to have forgiveness from Allah Ta'ala.

The name "Talha"

Q: I have choosen these names (Inhaan) (Mavin) (Minhaan) (Oruj) (E-Shaan) (ihaan ) (Aanis) (Talhaa ) (Danyaal) for my newly born son . Tell me which one is suitable for my son.

Interest

Q: If I loan someone money, for example, I loan someone R10 and we agree that they will pay me R15 in 10 months time, R5 more than what I loaned them, is that extra money considered interest?