Hi,

Well I am assuming that two of your back papers are left to be cleared. Considering that, I would suggest you to contact the university office to re-register for the back paper. Usually back papers are given in the comparative semesters, for example- back paper of first semester will be given in third semester and so on. Since you have a gap of three years, it will be best if you contact the office to either manually complete the process or ask for another way of doing so.

I hope this helps.

All the best.