In vale of shadows have two keys there is a door i cant get past, how do i use a key? Its in the inventory, i try to click on it and then leave the inv screen to see if my cursor changes, nothing. The satchel putton in the bottom menu is blacked for the character holding the key so i cant try that please help quickly! Thanks.

Yes, as long as any one of your characters has the correct key in his backpack, you just click on the corresponding door and it will open. Hold onto each key that you find. In the Vale you will also find at least one symbol and one talisman that don't look like keys but will unlock certain locked doors (they work the same as keys). As soon as you finish all of the quests in the Vale you can safely dispose of the Vale keys as you won't need them again in the game.

it is my guess you have the keys but are missing the symbol of Myrkul-Xavier