Suggest Ways To Rebuild Arches And Strengthen Weak Achilles Tendons

Hi! I have fallen arches and very weak achilles tendons (they are almost not "visible" so saying). My achilles tendeons are not strong and visible as it should be. The outside of the foot also "separates" from the rest and flattens out. Please give me some advice to rebuild arches and strenghtening my weak achilles tendons and my muscles in the feet.