Well firstly a single day of bad luck is not really indicative of a curse, it's usually just that you had a bad day, however there's no harm in doing a cleansing to be on the safe side. Probably one of the simplest is a salt bath, there's a few posts about it across the site but the basic premise is quite simply to take a bath in salt water, many prefer sea salt where possible. Wash in it, it may be an idea to be submerged temporarily, dry off and you're done although it's often necessary to do so more than once.
If this doesn't appeal to you or you just hate the idea of getting wet then other popular methods include cleansing yourself and home through smudging, praying to any relevant deity for aid, and many other practices. There are many other forum posts on this topic and one of the more helpful ones (http://www.spellsofmagic.com/read_post.html?post=470873) contains some great advice in the last couple of posts particularly.