Alright so yesturday I tried to downgrade the firm ware on my iPhone and needed to change the host files on my Mac. For some reason my mbp wouldn't authorize me to do this so I searches some videos online and finally figured that in order to do this I needed to right click on Macintosh hd, choose get info, looked st the last tab and selected my user as authorized to read and write files. I clicked some button ( IDR the nAme) and a loading screen popped up saying authorizing all files. I thought I figured it out till error messages started popping up so I panicked and decided to restart my comp. Now it's been on the white apple loading screen for 9 hours What should I try first to fix this? I've heard of clearing pram or something or is this only fixable through a reinstallation of osx???