Before you chemical treat, you should try making a homemade sea salt spray to get some curls back in your hair.
I suffered from a similar fate last summer when I did keratin treatments back to back on the front portion of my hair, leaving me with stick straight hair in front and curls all through the rest of my hair.
After soooo much trial and error, washing my hair with sea salt and the harshest shampoos almost daily, even using malibu crystals (a product used to strip color from hair), I finally came up with a solution.
I made a home made flax seed gel from a recipe on this site, then added one and a half teaspoons of sea salt to every 1/4 cup of gel. I diluted this solution enough to spray out of a spray bottle, and then voila...
I had curls back in my hair!!!!
Try this. You may not have to cut/process your hair.