Go to the left and you'll see Ron standing by a closed door. He'll open
it for you, so enter.
It should be easy to find the Wiggentree Bark, so I won't bother with a step-by-step walkthrough. But all I can tell you is to dodge the Prefects, slip past them when they're not looking, and enter a room with four shelves. One of them contains Wiggentree Bark. Don't be scared if Snape approaches, just don't exit the storeroom by the doorway! You see the bookshelf on the wall in front in the storeroom? If you don't know what I'm talking about, look for a dark shape where a bookshelf is in the dark. That's a secret doorway! Search the bookcase to open the doorway, and run outta here!
"You found Wiggentree Bark! You can practically taste that Wiggenweld Potion now! Or maybe you just inhaled a spider."
Oop, out of the storeroom, into the fire! You now have to escape an enemy-infested place back to your Common Room. As many were baffled with how to get by, I shall provide a step-by-step walkthrough.
1. Go to the left and wipe out any gnomes you see. Go downwards and go right. Knock out the gnome and press the pressure plate at the end of the corridor. Return, and go downwards a little more and you will see a chasm with the bridge the wrong way round. Wait until one of the spiky snails crawls onto the bridge, then fire three quick Flipendo blasts into its body. When it's destroyed, the bridge will flip over.
2. Go over the bridge, take out the spiky snail, press the pressure plate to the right. When the bridge flips over again, cross it and press the other pressure plate. The first pressure plate will then pop up, so go over the bridge and press it again. The bridge will flip again.
3. Now backtrack alll the way across the flipped bridge, and you should see another pressure plate has mysteriously appeared! Press and go downwards across the bridge, and keep going down until you see an open doorway. Go through.
4. Now take the right way, and go across the bridges, patching up gaps with Flipendo Blocks, and at the end, shoot the gargoyle with Flipendo to make it move. Double back and take the left way this time across the moving platforms to the door, and while the gargoyle is on the pressure plate, the door is open. QUICK!
5. Through the door and into the next room you go, knocking out all three blue gnomes. When they are out for the count, the door is open, so go through.
6. Now you find yourself in a room with lots of cracks, and a few gnomes. Run across the room quickly, those cracks become pitholes. When you enter the next room, avoid the two spiky snails and dash for the next room on the right.
7. Go upwards through another door (or downwards if you want a Chocolate Frog from the locked chest), go left and downwards, past the Tentacular, and press the pressure plate (the platform is not moving yet, but remember where it is), then go a little more left and through the open doorway. Push the pressure plate in there, double back to where the Tentacular is, now this time go to the right and through another open doorway and push the pressure plate there.
8. Now double back yet again, and you'll see the platform previously is now moving. Get on the platform and ride to the other side, then exit the place. Finito!
"You escaped the potions storeroom! Better get back to Gryffindor...Snape could be close behind!"
Outside the Dungeons, Ron is waiting for you. Now go allll the way back to the Common Room. There are few Prefects, but some walk really quickly, so be careful. Percy is guarding the bookcase, so you can't use it! Darn him! So you have to take the long way round. The puzzles starts on Floor 5, so when you go through the door...
1. Go upwards and take a right (Remember the location of those two bookcases nearby). You see that barrel and pressure plate over there? Go to the right of the barrel (on the pit's other side) and push it on the plate.
2. Go downwards and onto the only moving platform (the other one is stationary). Where it stops is a piece of land. Go onto the land and you'll see a Flipendo switch and a bannister. Fire a Flipendo blast over the bannister and flip the switch.
3. You've now gotten another moving platform working. Go on it and let it carry you to the other side.
4. Now keep going right until you find another barrel and pressure plate. Push the barrel onto the pressure plate, which enables the first stationary moving platform you saw in Step 2.
5. From there, go left and up another looooooooooonnnngg corridor. When you reach the end you'll see a huge chasm and many moving platforms. Go all the way across the moving platforms (carefully!) until you reach a small piece of land with cracks and a Flipendo switch. Flip the switch and make sure you don't step on the cracks, not even after you flip the switch - they become pitholes.
6. Get onto another moving platform and let it carry you to a piece of land which has two cracks and a chest on it. Use Alohomora on the chest to get a Chocolate Frog, and use the moving platforms to get you to a narrow area left of the treasure chest. You see a weird object there? Use Avifors on it, and it flies away!
7. Now go alllllll the way back to the beginning where you saw the two bookcases...WAIT! There's a secret door that was originally not there! Go through, and make your way across the chasm and out the door at the end of the corridor on the right!
Whoa! You find yourself in a weird room with a Mirror! This is the Mirror of Erised (desire), so go to it, and you see an illustration of Harry looking into the Mirror and seeing his deepest desire...to meet his long-deceased parents. Then...oop, Dumbledore finds you and you have a short discussion with him before he leaves the room. Now leave the room yourself and pick your way back to Floor 7, your Common Room. It's easy enough, seeing that prefects no longer are stationed at strategic points, so you can literally take the most direct way to each staircase.