cannot find drivers

Hello,
my computer running windows 7 32 doesnt recognise the mega 2560 when it is plugged in usb.
I tried getting the driver in the device manager,, but there is no "mega 2560" driver to be selected in the arduino driver folder, and if i ask windows to look in the arduino driver folder, it says it cant find a proper driver. anyone know where i can download a driver?

thanks

Is it an official board or a clone?

Check the markings on the black chip near the USB connector, will be 16u2, cp2102 or ch340G most likely; If 16u2, that's an official/faithful clone, and official drivers will work. Otherwise, google that part number, your OS, and the word drivers, download and install those and it should work.