Question

what would happen if the earth rotates slower or stops rotating???

Answer 1

we did not get the oxgen vein because it helps to get oxygen If Earth rotates stop we will not get oxygen we will die so

Answer 2

If the earth rotates slower then the duration of day and night will be more. If it will stop rotation then their will be no night if it is facing towards sun and if in opposite direction then never day will occur in that region.
Hope it will help you