I back up the protein treatments. Gradually make changes on your hair regimen, don't overload your hair though, or you could end up with a mess.
Swear off heat for a while if you're trying to get your curls back. If you are to straighten your hair, use LOTS of heat protectant, and make sure your hair is really moisturized and in top condition.
Start with something light, like a moisturizing and protein deep conditioner. I recommend the hair mayonnaise from Organic Root Stimulator.
Remind your curls of what they used to do. Get styling products and scrunch and finger curl your hair, or even do some pin curls for a while.
You may not be able to get your curls fully back, but it will bounce back and tighten up after a while after you do these things.