is there any free online certified computer courses which i can able to do with free of cost?
No! If you need a certificate then you have to pay a fees. But if you want to learn then there are lot of resources to learn for fee like Youtube, NPTEL etc.
Now I would say If you want to do a course with a IIT tag in it then go for NPTEL. NPTEL is a online learning program by the Government of India. There are numerous course in NPTEL. On giving a examination after course for a fee of Rs. 1000 you can get a certificate which will have a tag of the organizing institutes(mostly IIT's).
To know more about NPTEL you may visit the link below:
https://nptel.ac.in/
I hope my answer helps. All the very best for your future endeavors!