You could have a starter going bad, the cables themselves might be bad or the timing may have slipped too far advanced. TRy this before you do anything else. Try jump starting it from another vehicle. If it still turns slowly the starter is probably bad but, then again it may still be a cable. At least you will know it is not a timing issue if it starts right up.
your battery terminals may have battery acid build up between the terminals and battery posts, remove both terminals and clean with boiling water refit terminals and try to start again...same thing happened to me once...
As long as the engine is not running, you can wipe the starter casing down of any oil spilled on it. Since the battery delivers a substantial voltage to the starter which is required to crank the engine; you wouldn't want to accidentally touch the terminals on the starter when it was turning over.
First make sure your battery is fully charged. Crank the car, if the engine is turning over (moving) your starter is working. HTH
The starter could be bad. Or the battery. The starter could be bad. Or the battery.
It may have had enough power to run, but not enough amperage or voltage to operate the starter. Check the battery with a tester. Voltage should read at least 12 volts. If that is OK check the battery terminals to see if they are clean and tight. If you battery is fully charged and the connections are clean and tight check the starter by turning on your headlights and having someone watch them to see if they go dim when the starter is actuated. If they do go dim or almost out when the starter is actuated the starter is at fault. If they don't show any difference in brightness when the starter is actuated the solenoid at the starter is bad or the ignition switch is bad. Run a test lead from the + side of the battery to the s terminal of the starter . If they starter turns over the switch is bad. If the starter doesn't turn over the solenoid is bad.
Loose or corroded battery cables. Also possibly a bad starter solenoid or starter. Clean and tighten battery terminals. If it still does this, remove the starter and have it tested at any auto parts store.
You should locate and test the solenoid. Most have three connections. There is a large cable from the battery to the solenoid, from the solenoid to the starter and from the start switch to the solenoid. The power terminals to the battery and the starter are large and have large cables. The starter switch connection is much smaller. Turning the key to 'start' provides a low current voltage to the solenoid causing the solenoid relay to close and power from the battery cable to connect through to the starter. If that voltage is present then the solenoid or the wiring between the solenoid and battery or solenoid and starter is suspect. If that voltage is missing then the starter switch or solenoid feed line may have failed.
check the battery or battery cables or the alternator or starter
Terminals or the battery it self are not securely fastened in the vehicle.
Check your power . Battery and see if it is charged.
Its because your battery is "dead" OR your battery terminals aren't making good connection to the battery post they may need tightening
Does the engine turn over and then make the clicking noise while trying to start, or does it not do anything but make the clicking noise when you turn the key. If its not turning over at all then it might be a battery problem, Try cleaning the battery terminals, and/or charge the battery, Could also be the starter solenoid, but start with the battery first.