Dying Samsung SGH-X497

I've had this phone for at least two years now, and it's been in good working order for the longest time. Just recently though, my phone has been shutting off on its own. Sometimes after turning it back on after it shuts off by itself, my contact list and everything saved onto the cell phone will be wiped. Everything in my cell phone has been deleted at least five times due to the shut offs.

I've noticed some things that may help people give me advice. My phone sometimes feel hotter than it should be, almost like a computer overheating and running louder during the summer. Also, my cell phone seems to shut off the most during the day. During the night, the cell phone seems to be fine.

Help please?