I have turned switch on on outside wall to ON, checked the electrical box in the garage and it seems to be working, installed a new filter in the furnace, set the thermostat to 68 degrees and it still shows temp at 77. What isn't working?

Is there an inside thermostat? Set to cool and auto(fan setting on auto)

Is the outside unit running?

If so,when was the last time it was serviced?It could be low on coolant and simply need a charge.

A regular seasonal service call is recommended by most service workers in HVAC trades.

Does the indoor fan run?
Is the outdoor unit running?