I have overwritten my roll number in the attendance sheet of meet 2021 but filled the bubbles correctly ...will it affect my result .....if it does what should I do to prevent it
You need not to worry about that because your roll number will not be considered by scanning the number which you have written but it is considered by scanning the bubbles you filled on your omr sheet.
If you are really sure that you filled the bubbles corectly then you need not to worry at all.