My Galaxy Ace doesn't get recognised by my HP laptop with USB connection. When I tried to connect it with my friend's cable on his Dell laptop, it notified CONNECTION UNSUCCESSFUL - NO DRIVER FOUND. My phone still gets charged though. When I tried the `*#7284#` solution it wrote:

    DIAG CONFIG
    [1]USB[*]
    [2]UART[]
    [3]DBG MSG ON[]
    [4]DBG MSG OFF[*]

I selected `[1]USB[*]` and it gave me:

    USB_Diag Selected
    Change Complete.
    IF you change Uart or USB diag
    Please reboot the mobile.

I'm not able to find MODEM->PDA mode.