I need to know what driver i need to download and where for my casio ctk - 720 keyboard

The keyboard should stand alone and NOT require any driver. Drivers are for PC's,

Now if you are trying to connect the keyboard to a PC, then that is a different story. You did not mention that.

For tying a keyboard into a PC there are both USB and MIDI connections. You haven't mentioned using either.

When talking to a keyboard you will need music editing software, not a driver. That software you purchase SHOULD have what you need as part of it. There are also editors for the parameters in the keyboard. MOST of that software has to be purchased, although you sometimes can find shareware. Some can be quite expensive.