These are spells from a variety of sites. I do not know if they work, since I have never attempted them. Perform that at your own risk.
You need a strand of your hair, an nail clipping, a drop of blood and boiling water.
Mix them together whilst saying
"I beg to be wolf in dark and light
I beg to be a prowler of the night
I beg to thee to make it soon
I want to be wolf at the next full moon"
Bury the mixture under a tree, and wait untill the next full moon. When the next full moon comes, go back to where you buried it, water it. And you will feel a strange feeling, then you should change.
You need a toe nail clipping, a finger nail clipping, a drop of your saliva, 5 strands of your clean hair, a Lycanthropous flower and a full moon.
Sitting under a full moon, whilst chanting:
"A wolf's true from for all to see
Guided by spirits, I turn to thee
Give me the power of eternal night
So I may wander under moonlight"
Put all your ingredients together, and crush them in a clear small glass. Must be clear, no ridges, no pictures, just a clear glass. Then after chanting for 5 times round, you should feel a surge of energy run through you. When you get this, stop and you should be ready for the next full moon to change. You will experience some side effects - headaches, aching muscles - it's all normal. If you do not feel this surge, keep trying. Reliability shows that this works on 99.9% of people.