Is debt just a money or it is any object we took from someone? For example when I was kid about 11 years old, sometimes I took from my friends games. Now I have some games which are not mine but I don't know from whom I borrowed it, because latter on we split, everyone went in different school. Can i be in paradise if I don't return them?
Muhammad (s.a.s) once said:
Lending is ten times better than giving money to beggers, because beggers do have money, but lendees genuinely need it.
however he also said:
The person who borrows something with the intention of not giving back is a thief.
Due to your age at that time, I reckon it may just be fine.