Since I have access to this right now I'll post the codes.
First, assuming you have a North American keyboard, bring up the tilde key (
~) while in-game (it should be directly to the left of your number one key). A box, the console, will appear.
I don't know precisely if you need the the letter or ledger, so I'll give you both:
For the ledger, type into your console
exactly as follows:
'Player -> AddItem "bk_ynglingledger" 1'
*Now hit your "
Enter" key
For the letter:
'Player -> AddItem "bk_ynglingletter" 1'
*"
Enter" key
If your commands turn a purple shape you have done it right, and you will find the desired item in your inventory. The console is space and format sensitive so keep on trying if you don't get it the first time.
btw, welcome to Game Banshee!
