Keg not pouring

I brewed some beer a while back, put it in the keg like 10 days ago, went to get a beer and only a drop came out. I checked the co2 tank and it is 3/4 full, made sure the pressure was correct it is on 12psi like I always keep it. Turned off the flow of CO2 and relieved the pressure, opened the keg and I got a small sheet of ice on the top of my beer. I am thinking the outlet might have ice in it towards the top. So I am letting it sit outside the fridge now. Has anyone have any other ideas of what might be going on? Has any one ever had a problem like this? I just want to drink my dang beer!

If it is icing you need to adjust your thermostat. I would start with that.

I had a beer freeze up because the back of the keg was touching the fridge coils while the temperature controller probe was measuring on the front side of the keg. So I had a gallon of concentrated lager and a 2 gallon ice cube.