could be a couple things, what spells did you cast? most spells under trick or fantasy don't work because magic cannot change you into someone or something else, as well, it can't make you grow wings, or cat ears, make you fly or anything else against human nature.
for argument sake, say you cast a love spell. when did you cast it? the moon phase can effect a spell. the waxing phase [new to full] is best for spells drawing things towards you [a new love] while the waning phase [full to new] is common for spells drawing things away from you. [taking away feels for an old love]
did you cast a circle? there are people who don't cast circles when they are preforming spells [kitchen magic or cleansings] but you should always cast a circle, you'll be connected to the Lord and Lady, be in a sacred place best for magic, and you'll have extra energy around you to draw from as well as protect you.
third, you might not of charged enough energy when you cast. there's many different ways to charge with energy, most common while meditating. did you visualize/feel energy entering your body, then focus it on an item used in the spell?
those are usually the reasons why a spell doesn't work. check all your bases, if you've done all that and the spell still didn't work, it might not of been meant to be. OR you might not of put any effort in. after casting the love spell, did you talk to the person? or make an effort to meet new people? magic helps you to up the odds in your favour, you can't just sit on your couch and wait for it to happen, you need to take matters into your own hands.