Need Help no power when key in ignition
 

Don't know what happen but for some reason when the key is in the ignition there's no power? I checked all the fuse and everything is fine. So what could cut power to the igntion switch?

A bad ignition switch. There are probably a number of things that could cause it though. Did you check the fuses in the engine bay? Maybe get your battery tested.

it turns out to be the main fuse

oh then someone probably put the ground to the positive and positive to ground. I accidentally did that once and blew my main fuse.

My dad blew my main fuse by digging around with a screwdriver and shorted the 12+ terminal on the alternator to ground (which is the same as directly connecting the 12+ to - on the battery). I was so mad, it was my first day with the car and I had to leave it at their place overnight because the shops were all closed by then. I've heard that switching the + and - cables on the battery can do a lot more damage than just blowing the main fuse. Regardless, DON'T DO THAT and DON'T SHORT 12+ TO GROUND and this should rarely happen.