Hard Drive replaced and now experiencing touchpad issues

I've replaced the hard drive in my Dell Inspirion n5110 with a hard drive from Dell.com. Since installing, I have ran my two back-up disks. When the computer goes to 'register' the computer, the mouse is no longer working. I'm able to tab through the prompts, however when I need to accept the terms and conditions, nothing works; No 'ENTER' to select, no mouse (obvious)...I'm stuck. I've downloaded the touchpad driver and attempted to boot from CD, however it won't load; it gives me the RAMDISK and changes the drive to f:\. Please help!