i have 3G since 3,5 years now, what happened yesterday for the 1st time since ever - is that the phone has

Hi everybody!

I have 3G iphone since 3,5 years now, what happened yesterday for the 1st time since ever - is that the phone has switched off itself even when was charged n since then it refuses to reboot ! Indeed, application says - Enjoy your jailbroken phone ! What would that mean ? Any chanses to get that phone On ? (or does it mean the phone gone old n i should get a new version of iphone ?)

Thanks in advance !