Mirage Problems please help!!

I have a 1998 Mirage Standard, and i've been having problems with it. Sometimes, I turn the key and it doesn't even turn!!! Plus, my stereo deck is running straight off the battery and when I turn on the headlights, the deck shuts off! Is it the battery? If anybody can help, i appreciate it in advance!!!!

Sounds like a bad battery. The headlights draw more current to run than the stereo. If the starter will not spin when you hit the key have it checked by a Mitsu Dealer to see if it is the battery or the charging system. The alternator , new for these cars run $150.00. A battery runs 69 bucks. I had my alternator replaced new and the dealer charged me almost 250.00. Also the headlights run off the battery when they are on. The alternator is used to keep the battery charged while the car is running as well as supply current to the circuts in the car. Check the drive belt to the alternator to
see if it is loose, worn and frayed, cracked (dry rotted)
John