I recentaly decorated a room and took raditor off the pressure
has gone down so i took your advise and i could only find one switch to turn not two like you saide pressure gone up to one bar but radioter not heating up
Turn both radiator valves fully on (one will be hand operated, the other one turned with pliers usually) - then open the bleed valve at the top of the rad. to let the air out. Keep topping up your boiler as you do this.
