I have recently given CA foundation paper in law paper I forgot to mark the question I have attempted in paper as given on the 1st page did it will affect my paper

Harsh  It totally depends upon the Examiner, because if the student is clear in language while answering, the first two lines will give the Examiner an idea as to which question has been answered. For future exams, don't only depend on the number of question answered, but also mention the heading in the answer at the very start. Because one might have mentioned the answer no. correctly, but a confusing start to the answer might mislead the Examiner. If OMR answer sheet where details are provided through OMR, it can be the 'Total number of questions attempted' In that case, it won't at all affect the result.

I have recently given CA foundation paper in law paper I forgot to mark the question I have attempted in paper as given on the 1st page did it will affect my paper