I stepped on my foot the wrong way and twisted my ankle and its swollen. is that a big deal?

Ankle Sprain: Ankle sprains are fairly common, and can take several weeks or longer to heal, depending on the severity. If you aren't able to put weight on it, i would recommend getting x rays to make sure it isn't broken. Otherwise try rice (rest, ice, compression, elevation) and ibuprofen.

See a physician: It may be a bad sprain or could even be a fracture. See a specialist of the ankle for x-rays and examination.

Probable sprain: Without a proper evaluation, it's hard to say- but sounds like a sprained ankle- which responds well to rest, ice, compression, and elevation. Depending on the severity of the sprain, you may need a walking boot or brace.