make sure positive cable is connected to positive post on battery. negative cable connected to negative post on battery.
Loose battery or alterator connections
Check your battery voltage with a voltmeter. Also check your battery grounds / battery connections for acid corrosion.
Corroded battery cables. Remove the battery cables, negative first, and clean the cable connections and the battery posts. If that does not help the battery needs charging or is defective.
If the headlights flash on and off, there may be a problem with the bulbs or fuses. There may also be a problem with the battery connections or wiring.
Sounds like the battery went dead or you have loose/dirty battery connections.
check your fusees first, if it is an after market radio check your connections also check battery connections
because the battery is the source of the power for the headlights. there could be an issue with the battery or the alternator can be failing.
Check to make sure all connections to the starter are properaly installed, Check battery connections to see if their is corrision, or check cables from battery to other connections are not loose, if so, correct them, you can also check for burn't out fuses or relays related to the ignition.
Could be a dead battery. Put your headlights on and go out front and look at them. If they are not on or very dim you may have a dead battery or dirty/loose battery connections.
turn the key? no start? check the battery connections. clean them make sure they are tight turn the key no start? turn on the headlights if you have bright headlights, the starter may be the issue. if you have no headlights, look at charging the battery after battery charge turn the key tries to start or clicks probably a dead battery if the car turns over and just won't start do you have gas? If the car turns over and tries to start that means the battery and starter are good now you need to find out why you are not either getting spark of fuel.
What are the symptoms? Will it turn over? Can you turn the headlights on and are they bright? IS there a clicking sound? Did you clean the battery connections? The side terminals really need to be clean to send the best current to the starter especially in the winter. Try cleanign the battery connections FIRST before you go any further then check back with another posting on what you have checked.
On the top of the battery unless it has side connections which are on the side and are not posts but female connections.