I've read the other posts on where to find the writ to enter the stout mines (some say to the north while some others say to the east...) but I swear I have searched everywhere! Is it possible that I have already picked it up and prehaps sold (I have gone to see if I could buy it back, if this was the case)? Is the burnt body still there after you get the writ..... ?
someone help me out, PLEASE!

Yes the burnt body stays there but to be honest I do not remember where I found the chest and body at (maybe near the castle but I am not certain.

An alternate approach: talk to the guard asking for the writ until you start getting a message about how thirsty he is. He says he will give ANYTHING for a drink. I gave him some booger brew and he gave me a writ that I had "lost".

You will know it when you find it for sure.... the game narrator starts talking -- telling you something about coming up on the burnt corpse etc.
It is to the north of the mines..between the dragon spire and the mines. If you have a map to look at you will see between these two places a little squared off path that runs between them, kinda....with a path that deadends in the center of the square.
You will find it on the path that deadends in the center.