My 2008 Honda Civic has been turning over slowly, but failing to start on the first couple attempts to start it lately. Sometimes it'll start first try, but typically it needs multiple attempts. My father thinks that this is an alternator issue. However, this morning it was completely dead, and I attempted to jump it with no success. Why is my car not starting?
If the car is silent, no starter noises then this may be a dead starter with several starts needed on almost every startup. This can lead to premature starter wear. There's a simple test but relies on a good battery and battery connections. With automatic in Park, parking brake pulled, front jacked up to see starter terminals, short two terminals on the starter solenoid - small terminal to large terminal with battery cable attached. This should result in the starter engaging and cranking the engine immediately regardless of ignition switch position (leave ignition OFF during this test). This tests the battery, battery cables, their connections and starter all at once. If the starter doesn't run or grunts, the starter may be worn out, battery is faulty, battery cables loose or corroded and won't provide high amperage to the starter. If the starter runs then there's either a fuel or spark issue.
The root problem may well be the alternator since if it were bad or failing the battery would not be charged between starts and eventually you'd get to the point where there is no enough energy left in the battery to start the engine.
But the first thing to check is the battery connections. Be sure that the connectors on the battery are tight and free of corrosion. Also check that the cables themselves are not damaged and that the non-battery ends are firmly attached.
If that checks out, then take the battery to a shop and have it load tested. This will give you a health status of the battery. If it passes then the problem is elsewhere, like the alternator. If it fails, then you should replace the battery.
Now check the alternator drive belt and make sure it's properly installed and not slipping. An alternator that is not properly driven can fail to charge.
At this point the alternator may still be bad so you can either check the battery voltage with the engine running and see if it's around 14V.
If it's too low or too high, it's probably the alternator. Many shops can test the alternator if you remove it and take it to them.