my battery died last night, i charged up my phone and when i turned it back on its stuck on the start up screen, its really really slow, if i press dow it actions it about 5 mins later, i cant access any other part of the screen other than the start up screen that shows options like messges and mail etc, my boyfriend rang it before and it was ringing from his phone but my phone wasnt doing anything, when it first starts if im relly quick i can get into messages but then it freezes, any idea's how to fix this ?? 