Student or Learner
I have a doubt about these two sentences "Nothing can't stop me or Nothing can stop me." ?
The first is incorrect. It involves the famous "double negative" - "Nothing" and "can't". The second is correct.
Please look at my corrections above in red. There was no need for a question mark at the end. You didn't ask a question. You made a statement - "I have a doubt ...".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.