A single click with each turn of the key can often be a frozen/bad starter. The solenoid kicks out the gear but she can't spin, result- a single click.
Multiple clicks while holding the key in the start position is usually a weak battery, kinda like tic,tic,tic,tic,tic,etc.
Another thing to check for is your lights, if they completely dimm out probably bad battery. If you get the single click and lights are still operating, bad starter.
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