That blue powder and the fact that your car won’t start tells me your battery is probably 4-5 years old, and is probably due for replacement. Many auto parts stores will test your battery for free, and many will even install it without charging for labor. However, auto parts store employees are not mechanics, and you need to check their work to make sure the battery is secured properly. Get your battery tested for free, and I bet you will be buying a new battery soon.