Well at least we have something to work on. Let's check the gas post by taking the cold keg out of the fridge, set gas bottle at 30psi, connect to keg gas post and lay the keg down. Rock the keg back and forth and you should here fairly loud bubbling of gas, if not the gas post is the problem.
*****WARNING***** do not do this if you do not have a non return valve for regulator protection.
If all ok let's get some carbonation going. Rock keg back and forth for 90 seconds at the 30 psi, then stand keg up and remove disconnect. Put keg in fridge again and leave for a couple or hours to settle. Then release pressure in keg, set gas to pouring pressure and connect. Leave 15 mins and pour a beer to see how it is, my need to leave overnight on the gas.