After the Leaky Cauldron hub area is unlocked, enter Wiseacres Wizarding Supplies in Diagon Alley. Go upstairs and talk to the vendor, then enter one of the following passwords to activate the corresponding cheat function.
Effect
Code
Spells
Accio
VE9VV7
Anteoculatia
QFB6NR
Calvorio
6DNR6L
Colovaria
9GJ442
Engorgio Skullus
CD4JLX
Entomorphis
MYN3NB
Flipendo
ND2L7W
Glacius
ERA9DR
Herbifors
H8FTHL
Incarcerous
YEB9Q9
Locomotor Mortis
2M2XJ6
Multicorfors
JK6QRM
Redactum Skullus
UW8LRH
Rictusempra
2UCA3M
Slugulus Eructo
U6EE8X
Stupefy
UWDJ4Y
Tarentallegra
KWWQ44
Trip Jinx
YZNRF6
Bricks
Gold Brick 1
QE4VC7
Gold Brick 2
FY8H97
Gold Brick 3
3MQT4P
Gold Brick 4
PQPM7Z
Gold Brick 5
ZY2CPA
Gold Brick 6
3GMTP6
Gold Brick 7
XY6VYZ
Gold Brick 8
TUNC4W
Gold Brick 9
EJ42Q6
Gold Brick 10
GFJCV9
Gold Brick 11
DZCY6G
Cheats
Carrot Wands
AUC8EH
Character Studs
H27KGC
Character Token Detector
HA79V8
Christmas
T7PVVN
Disguise
4DMK2R
Extra Hearts
J9U6Z9
Fall Rescue
ZEX7MV
Fast Dig
Z9BFAD
Fast Magic
FA3GQA
Gold Brick Detector
84QNQN
Hogwarts Crest Detector
TTMC6D
Ice Rink
F88VUW
Invincibility
QQWC6B
Red Brick Detector
7AD7HE
Regenerate Hearts
89ML2W
Score x10
H8X69Y
Score x2
74YKR7
Score x4
J3WHNK
Score x6
XK9ANE
Score x8
HUFV2H
Silhouttes
HZBVX7
Singing Mandrake
BMEU6X
Stud Magnet
67FKWZ
Christmas in July
If you purchase and use the "Christmas" extra, the room you use it in will keep playing the same music for the rest of the game... Just like the red-haired Ron cheat, it will not revert back to its regular music.
Quick Coins
Find, post and purchase the "Collect Ghost Studs" extra. The parcel was either in Harry's bedroom or on the courtyard fountain (You will need to have learned the Leviosa spell first). Once activated the Ghost Studs are worth 1,000 each. "Get lost" the ghost will return to you and lay more studs -- it's easy money. A full trip from the Dorm to the Great Hall is worth about 100,000.
Red Haired Ron
After completing the first two levels of the game, you should have enough LEGO Pieces access this Easter Egg. Go into the wizard town through the Leaky Cauldron, the last shop on the left (before the bank), sells custom spells. Purchase the spell called 'Multicorfors'(a spell that turns the characters into "gingers"). Cast it on Ron Weasley. Once cast, he will shake his head as if it has worn off, but his hair will not revert back to its natural color.
Red Sparkles
In order to do away with the objects with red sparkles around them you have to use dark magic. In order to use dark magic you need to use the Polyjuice Potion (or use an evil character on freeplay -- e.g. Lord Voldemort, Tom Riddle or Barty Crouch Jr.). Evil characters' Wingardium Leviosa spell is changed to the Crucio curse (but works just the same as Leviosa) and can now destroy the red sparkly objects.
Unlimited Ghost Studs
Whenever Nearly Headless Nick is floating still (and you have the Ghost Stud extra on), stand under him and he'll constantly give you ghost studs.
Cheat Mode...