How do I get my hair to return to being as curly as it used to be?

[Stéphanie]

In the last few months I have noticed that my hair seems to be getting straighter, but only certain parts of it. The top of my hair is curly, as well as underneath. However, the middle of my hair is almost completely straight! It drives me crazy. I have tried several product, from mousses to gels, to serums to sprays. I am at a complete loss. My hair is becoming very difficult to deal with. It seems that for my hair to hold the curl it has I have to use far too many products and too much of them. I prefer my hair to look natural, but when I leave it looking that way it always falls flat and loses a lot of the curl throughout the day. If I use a lot of get/mousse/spray whatever it might be, my hair ends up "crunchy" but the curls are more defined and stay throughout the day. I do not like my hair being crunchy. Any advice as to how to get my hair back to being as curly as it used to be? and how to do my hair and keep my curl without it being crunchy?