What must I do with my suck Blackberry Bold 9790 phone?

My blackberry won't charge in the electric socket. If it's charged in the electric socket, it will have a red light for a while and then have a battery symbol with red cross on that symbol on the screen. Someone in the internet said I must install the new OS software from Blackberry Desktop Manager in the PC (I use Windows 7 Home Premium) and it must be wired to PC without its battery. When I do that, my computer didn't recognized even though I clicked "Retry" and I unplugged and plugged it again thousand times. He/she said I must click "Upload" if the condition is like that. I did that but it didn't work. Then I unplugged my blackberry and then I entered my battery (JM1) into my blackberry and wired my blackberry in to PC again. My PC didn't recognized my blackberry but my blackberry have a battery symbol with yellow lightning symbol on that symbol on the screen. I'm sorry if there was a wrong words because I'm not from English language country. Now I ask you "What must I do?"