Much depends on context.
The first sentence says the he could not do one or the other.
The second sentence says that he could not do both at once.
It is difficult to figure out the intended meaning.
Student or Learner
Which is correct between the following two sentences. Thank you.
He was unable to talk or walk.
He was unable to talk and walk.
Thank you so much for your kind reply, MikeNewYork sir.
giddyman, there is no need to write a new post to say Thank you. Simply click the Thank button on any posts you find helpful. It means that we don't have to open the thread again to read your new post and then find that it doesn't include any new information or an additional question. It saves everybody's time.
Please note that there is no need to write a new post to say "Thank you". Simply click on the "Thank" button in the bottom left-hand corner of any post you find helpful. Also, there is no need to use things like "sir". It is unnecessarily formal and you cannot be sure that the person you are addressing is male.
Edit: Cross-posted with Rover.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.