Today i stood up and hit my head on an open cabinet door (the sharp corner). could this cause a brain aneurysm to form? or a closed skull fracture?

No and unlikely: It will not form an aneurysm and it is unlikely that you have a skull fracture. Skull bones are quite sturdy. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.