Help Samsung Anycall Galaxy S keeps restarting

Hi good day!

I am asking for your help on how could I able to recover my phone from being a defective one.

Its major issue is, everytime I turn it off or even automatically turning off because of low battery my phone won't able to start and it will keep restarting over and over again..
I always try recovering it by rebooting but it makes a total hassle because my apps, contacts and all installed apps. are being affected, i want it be in good condition and works normally.
Please help me what to do..

Thank you..
God bless.