Previously, I used not to perform the prayers. Allah blessed me with guidance. I became very keen on performing them. My question is about the prayers in all of those previous years that I missed. Is it obligatory upon me to make them up or not?
ANSWER

`Abdullah ibn Abdulrahman ibn Jibreen
10 February, 2021
In the Name of Allah, Most Gracious, Most Merciful. 

All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.

In this fatwa:

When a person abandons prayers for a number of years and then repents and performs them regularly, it is not necessary for him to make up the prayers that he missed.

Answering your question, Sheikh `Abdullah ibn Jibreen, the late prominent Saudi Muslim scholar, stated:

When a person abandons  prayers for a number of years and then repents and performs them regularly, it is not necessary for him to make up the prayers that he missed.

Should I Make Up for the Missed Prayers in Order
Should I Make Up for Missed Prayers in Order?
If that were a condition, it would make many people flee from repentance itself. However, the repenting person is to perform the prayers regularly in the future and to increase his voluntary prayers, acts of obedience, good deeds, getting closer to Allah and his fear of Allah.

Almighty Allah knows best.