la plus utilisée = 1
1 formal - It doesn't matter.
1 formal - It's not a problem.
2 informal - Don't worry (especially to begin the sentence)
2 informal - Never mind.
2 informal - it's not serious (not a serious problem)
1.. I arrived late for the meeting, but it does not matter.
1.. I burnt the food, but it does not matter because we can eat at a restaurant.
2.. Don't worry, the food I burnt was not expensive.
2.. Never mind (don't worry about it), the food I burnt was not expensive.
2.. Don't cry, it's not a serious problem.