If you want to do anything other than charge your phone on your computer (eg transfer data to/from the phone) you have to install the storage drivers supplied with your phone. That's what I had to do with my BlackBerry.
I have a desktop PC and a laptop. The BlackBerry drivers are installed only on my desktop PC so it recognises the phone as a storage device.
However, my laptop does not have BlackBerry software installed so it does not recognise my BlackBerry phone as a storage device.
So I know for sure you have to install drivers for the phone to be recognised as a storage device. The drivers were supplied with my phone on a mini CD.
If your phone has a removable memory card, buy a card reader. Connect the card reader to your laptop, then put the memory card into the reader. You don't need to install any drivers if you do it that way because the required driver is built in to Windows.