there is so much bad in the world......how do i keep believing?

with my dad being sick and my grandma slowly getting worse and the death of my grandpa, my pa, and my best friend it has got me thinking.... i know that god exsists but i dont understand why there is so much pain and hurt in the world. i stopped believing a long time ago because nothing seemed to be right. by that i mean i saw nothing but bad things going on around me and no matter how much i prayed nothing seemed to get any better. i guess what i am saying is i am slowly losing the faith again and i cant seem to find my way back. i still believe and i still pray but my daddy is really sick and today he may or may not make it thro this surgery and i am praying hard but im afraid it will do no good. my father is a great man. i may not have lived with him all the time and i may not get to talk to him much but he is an amazing person. he does everything he can to make everyone happy even if it puts him out but for him to be such a great person why should he have to deal with cancer? i know many people are going to want to argue about this but i am NOT looking to argue i just need to know what to do to bring the faith back. i need to know why all this happens. any thoughts are welcome just please dont be rude i have enough going on in my life right now.