Once the Leaky Cauldron hub area is unlocked, enter Wiseacres Wizarding Supplies in Diagon Alley before starting actual game play. Go upstairs, talk to the vendor, and enter one of the following codes to activate the corresponding cheat function:

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 x2----------------------------¦74YKR7
Score x4----------------------------¦J3WHNK
Score x6----------------------------¦XK9ANE
Score x8----------------------------¦HUFV2H
Score x10---------------------------¦H8X69Y
Silhouttes---------------------------¦HZBVX7
Singing Mandrake-----------------¦BMEU6X
Stud Magnet------------------------¦67FKWZ
Super Strength---------------------¦AKTR38 <-- this may not work.
Alt Super Strength code---------: BMEU6X

Alt Super Strength code thanks too "Xenety"
I've not tested it personally but let me know if you try it and it does work.

Gold Brick----------¦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

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

Go to the Leaky Cauldron after you have learned Reducto, and destroy the piece by the stairs (it will flash blue). Jump down, and you will be in a room with four areas dedicated to each year. You must collect all Gold Bricks for each level to build whatever it makes.

Enable the "Ghost Stud" extra option. When Nearly Headless Nick is floating and not moving, stand underneath him to keep getting Ghost Studs.

To destroy objects with red sparkles around them, you must use Dark Magic. In order to use Dark Magic, you need to use the Polyjuice Potion or an evil character (for example, Barty Crouch Jr., Lord Voldemort, or Tom Riddle) in Freeplay mode. An evil characters' Wingardium Leviosa spell is changed to the Crucio Curse and can destroy the red sparkling objects.

Successfully complete the first two levels, then go to the wizard town through the Leaky Cauldron. Enter the last shop on the left (before the bank), buy the "Multicorfors" spell, and cast it on Ron Weasley. Although he will shake his head as if the spell has worn off, his hair will remain red