My car doesn't start and i have no clue to whats wrong with it. I turn the key in the ignition but the car just keeps cranking. Any help will be useful thanks.

 

got gas in the car? battery terminals on right and tight?

 

I checked the gas and it's close to half a tank so thats not it. The terminals battery terminals are tight. The thing is when i was driving yesterday my whole sound when out. My deck didn't turn on or anything. I checked it and it blew the fuse. I don't think thats the cause that my car wont start thought. Any suggestions? Can it be the starter or alternator? Any help will be very useful thanks.