A/C not working

[Hadiah]

When the nest thermostat was set up, both heat and a/c worked. At some point, when I was out of town, the a/c seems to have disconnected and now I can’t re connect it. I have heat but no a/c. I did a factory reset and I can’t get it set up. I can’t figure out how to send a pic but I know the wires are correct because it has worked for months! Now no a/c. Thank you for any help!

[CoolingWizard]

@Hadiah ,

Why on earth did you do a factory reset? Now you have perform a new thermostat installation. 
What type of heat do you have?

Ok, if your thermostat is calling for cooling, there should be power on the Y/Y1 wire at the air handler. 
Using a Voltmeter, check for the AC Voltage at the handler between Y and C. Whenever a Nest Thermostat calls for cooling it also  energizes the G wire.  So measure AC Voltage between G and C. Does the blower fan currently come on when the Nest Thermostat calls for cooling?

The Cooling Wizard