You can straighten your hair just by putting in some large foam or velcro hair curlers. Choose rollers that are large enough for your hair to go around just 1.5 times for a large "C" curl.  Your hair may not be pin straight if you have curly or textured hair, but it will look straighter. Get the largest curlers you can find. If possible, find some curlers that are about the same size as soda cans.  If you are not opposed to using heat on your hair, then using large hot curlers can speed up this process. Otherwise, go for some foam rollers and be aware that you will need to leave them in for quite a while.
اشتري بعض لفافات الشعر الكبيرة.