What quest do I need to do to get the skeleton key?

Its one of the shrine missions I can't rember wich one though

Poleio is correct, the Skeleton Key is gained by completing the Daedric Shine quest from Nocturnal, the Night Mother. Basically, the story goes that the original Grey Fox stole Nocturnal's Gray Cowl. In the present, two Argonians in Leyawiin have stolen the Eye of Nocturnal and you need to track them down and get it back. She must not be too scary if people keep stealing her stuff, seriously.

Either way, I'd say this is the easiest quest to complete but it requires that you are at least level ten(10) or above. In the quest, you're given the location of the shrine by Alves Uvenim in the Leyawin Mages Guild but unlike all the other shrines except for Peryite, you don't need to make an offering to the goddess. As long as you're a level ten(10), the goddess will speak with you.

During the quest within Leyawiin, you won't have a compass pointer and the topic of "Eye of Nocturnal" will reward you with nothing but a few suspicious eyebrows wondering if you're insane and some blank stares. But! Talk to any of the Imperial males in Leyawiin and you'll find out that Weebam-Na and Bejeen have recently been on a bragging tear about some "valuable jewel" that they just scored.

Side note: Weebam-Na is also present in the Miscellaneous quest of "Mazoga the Orc," and if somehow he died in that quest, you won't have the option of beating this quest, it won't even show up and the Skeleton Key is lost forever. Which isn't good because if you don't work your Security fingers a lot, you're going to be breaking a lot of lockpicks and burning through gold.

Either way, talk to Weebam-Na in his and Bejeen's house on the pond in between the Great Chapel of Zenithar and the Castle of Leyawiin. Go inside and speak to Weebam-Na and you'll get the awkward, nervous conversation of "Never heard of the thing...Neither has Bejeen. You ask too many questions."

If you speek to Bejeen, she's just as skittish as Weebam-Na and in both cases you're journal will suggest you eavesdrop on their conversation to find out what exactly it is that they're hiding. So leave the house, crouch into sneaking mode and enter the house again and you'll overhear a small argument about whether the Eye is safe from Trolls in Tidewater Cave. Aha! Your journal snaps into action and tells you to go investigate the cave which is on the Topal Bay coast a little southeast of the city.

Head to Tidewater Cave and you'll find that it's a low-level cave with no monsters, just animals of all shapes and sizes like bears but there are two leveled Trolls outside the cave and three within the cave. They're leveled so they will be tough against you but just deal some damage with a fire spell and they'll go down pretty quick. Inside, make your first left and then a left at a T-like intersection to find the Eye at the end of the underwater passage. Take the Eye back to the shrine and Nocturnal will trade you for the Skeleton Key which is an unbreakable lockpick that boosts your Security skill by 40 points!

Good luck, if you have any questions, just ask again or send me a private message and we'll get you through it.

The only thing needed is lv. 10, the location of nocturnal is on the western path from Leyawiin, heading north, tou then find the two argonions, spy on them, then find the cave where they hid it

You need to do a Daedric quest Nocturnal. Just go up the north path of Leyawiin and go slightly west and it is there. You need to be at least Level 10 to start this quest, and it is really easy. Have an invisibility spell handy or a high sneak level to make things more smoothly and quickly.