Battery is fully charged , fuses good , car will not start or even turn over , all connections appear good

These may seem obvious questions but have you checked any fuses? How old is the battery and is it fully charged? Sometimes an older battery can appear fully charged but is weak when 'under load'.

Look for a fuseable link in the wire harness. It is usually in a red wire and is more flexable that the wire it connects to.

type and year of is helpful so we`ll go generic----start by checking the connections at battery for corrosion or damage if good than check power to starter if none check wiring and connections also check power from ignition switch as well as fuses.also try turning key to accessory step on brake and move shifter to neutral than try starting if starts shifter may be out of adjustment or damaged this would be your basic troubleshooting for dead type battery when battery is fully charged but always recheck your battery that it is fully charged

You have a open connection even a open fuse start with the fuse there is a 120 amp that is for the charging system and there is a 30 amp fuse.If bothe fuses are good go to the alternator and make sure of your connection just because there on doesnt mean there good The choice tool for this is a voltmeter

start with the battery. needs at least 11 or 12 volts to start the car. By no lights, do you mean nothing, absolutely nothing comes on? no lights on dash when you turn key to on? If so, need to check battery connections. are they both tight and clean? Is battery fully charged? Before you can diagnose the car you musthave a good battery that is fully charged. Then you can try and start it. If it still wont start or crank over you may have a main fuse out that would be under hood near battery.

Has to be a cable connection issue of some sort. Check the other end of the battery cables, either the ground connection to the chassis, or power connection to the under hood fuse box. Could be that one of the battery cables has broken inside the insulation yet the connector looks good. Try using a cheap ohm-meter to see if there is a break in either cable ...keep looking!

Might be an engine relay or a various fuse. Check you owners manual for which fuses/relays might relate to the engine or ignition.

no if you have a good batt you don't need alt the alt charges batt after you start the car

Was the battery checked before it was sold to you? Batteries will lose their charge over a period of time even when not hooked up. If you have a voltmeter it should read 12.8 volts on a fully charged battery.
Have you tried to boost the car with cables?
I suspect if the car was working OK 3 months ago it should start. Which leads me to suggest an undercharged battery.

sound like bad starter solenoid or bad starter.