Computer can not detected Iphone

Dear Tech !

I was clean up but unexpected I deleted and wipe out all thing in my Iphone ... My Iphone just turn on or of power only,everything is black...I connect back to computer ..My computer can not read(detect Iphone) I was try press power and hold button home But it can not scan Iphone. ( my Iphone is 3Gs) Please tell me a way to solve it... Many thanks