Can you post the model number please.
Ok if you look through the vent at the top do you see any ice or frost in there?
Ok do you hear the fan running?
Also if you feel the compressor at the back is it hot to touch?
It has been switched off for 2 days but you could hear something running and the back was hot to touch
Ok if its been turned off for 2 days then it wont be a blocked evaporator. And as the compressor is hot then its a sign its not pumping correctly.
Im afraid for this is a system fault. Either its short of gas or its a poor pumping compressor. But you need to get a fridge engineer in as they will need to get there gauges on the back and see what pressure its pumping at.
But im afraid this part isn't a diy fix and its not going to cheap aswell.
As a new compressor fitted is about the £200 mark and a regas is about £140.
Sorry its not looking like good news but from what you say its a system fault here causing it not to get down to -19 degs.
If you need anymore info just get back to me.