resigned

  1. I’m resigned to not having any success in that field.
    1a. I’m resigned for not having any success in that field.
    Which is the right sentence?
    Are both correct?

Only the first option is correct.

Can I not say as below:
“I’m resigned due to not having any success in that field.”

no.
That is a different meaning of ‘resigned’ and it would require ‘I have resigned…’

You are thinking of ‘resigned’ as resigning from a job or position.
In the original ‘resigned’ means accepting of the fact that…