Harry Potter and the Chamber of Secrets/Lost and found

There are two sets of 'lost and found' or 'lost item' side quests which consist of finding lost items around Hogwarts grounds for students. They start off with some clues and end up being just general like 'could be anywhere'. These quests reward Harry with wizarding cards, beans and house points. Beware, a lot of loading screens await you on this quest, as it involves a lot of to and fro between the common room and the outside world. Also, all the items must be collected and returned in this order or the next item will not be there.

In the Gryffindor common room, there is a notice board to the right as you walk in if you press as you stand in front of it it will bring up a lost item notice with a 'clue' although these become progressively more vague with each item such as 'could be anywhere'. The item in question could be somewhere outside (or on top of) the Hogwarts buildings. Don't worry about a time limit – there isn't one so you can take as long as you like to find the item and you can carry the found item as long as you like. After you've found an item, return to the notice board.

Potion Vial Case
As you come out of Hogwarts main hall, take the path straight ahead of you to the greenhouses. Once you enter, go right, then left, as those are the only directions you can go. Go a traight down, and to the left after the greenhouse, you will find the potion bag.
 * Reward: Wizarding card, 10 HP

Merit Badge
Go toward Mme Hooch in the flying practice courtyard. Out of the hall, turn left onto the brick patch through the cloisters and go straight forward until there's a tunnel to your right. Go through and there she is. Turn towards the tunnel you've just traveled through and follow the wall to the left and you'll eventually see the badge sparkling in one of the walls.
 * Reward: Wizarding card, 10 HP

Telescope
Found on a rooftop connected to a pointy tower
 * Reward: Wizarding card, 10 house points

Neville's Toad
Neville is always losing things as you will find in this quest. Trevor, his toad, is outside the Herbology Greenhouse to the right. Flippendo him and walk over to collect him.
 * Reward: Wizarding card, 10 HP

Measuring Scales
Measuring Scales are between Hagrid's cabin/hut and the wall to the forbidden forest. They will be larger than most of the lost items, so should be relatively easy to spot.
 * Reward: Wizarding card, 10 HP

Wizard's Hat
Between Hogwarts and the Quidditch Stadium there's a small copse of trees seemingly in the middle of nowhere. In the center of these trees is the hat you are looking for.
 * Reward: Wizarding card, 10 HP

Dragon Hide Gloves
For these gloves, you need to go to the confiscated items store room. Go towards the flying practice field, continue through the tunnel straight in front of you as you enter the field and you should find yourself on a bridge. The door in front is locked. Now if you mount your broom and fly to your right (towards the lake), on the left below you is a green field where you should espy a sparkly lost item.
 * Reward: Wizarding card, 10 HP

Gadding with Ghouls
If you go back to the afore mentioned bridge to the confiscated items storeroom, but instead mount your broom with your back to the storeroom and fly diagonally forward/right, you will see a square of green with a lonely tree in it. In one corner you'll see the book.
 * Reward: Wizarding card, 10 HP

Holidays with Hags
This book is the penultimate item. You need to exit the great hall and go through the tunnel to the grounds. As you come out of the tunnel, turn right and follow the wall round until you see the book sparkling innocently in a corner.
 * Reward: Wizarding card, 10 HP

Tarantula
Lee Jordan's tarantula has gone missing, so head off towards Hagrid's hut. Go immediately to the forbidden forest wall behind the hut and follow the wall to the right until you see a small gap in the wall. Crawl through this by pressing, aim and Flippendo that spider sparkling and crawling about in the small paved area. It may take a couple of hits, but don't worry about hitting him too hard – he won't die.
 * Reward: Wizarding card, 10 HP