Wanting to reuse old Laptop parts for a DIY PiTop

It would depend on the keyboard and touchpad.  Most laptop keyboards and touchpads I have seen have a ribbon connector coming out of them to an interface on the motherboard and are not standard (a Toshiba keyboard won't fit in a Sony, etc).  You would need to disassemble the laptop and find out the connectors for the devices and then find out the pinouts for the connectors.  I think that without some additional hardware to interface the keyboard and touchpad to the Pi, it is unlikely to work.

Check this out....

https://www.youtube.com/watch?v=yOHws0qBBmI

Some additional info I forgot to include, if I recall correctly most laptop keyboards are dumb, just a bunch of switches laid out in a row/column format, and the keyboard controller is built into the laptop motherboard.  It should be possible to find a keyboard controller (possibly from an old keyboard) and map the pinouts of the laptop keyboard controller to the inputs for the keyboard controller and then the keyboard controller would provide you with the interface to the computer.  Depending on which keyboard controller you used, you could have a PS/2 or USB outputs. 

Thank you for all of your help. I've got the screen sorted, just the keyboard  and touchpad plus the left and right buttons to sort. the main problem is the touchpad, not really sure what to do, but can always us an external mouse. The keyboard I did wonder if I could use a controller from another one.  Doing some more research on you tube. A couple of videos i have found, they used a teensy but i don't know if this can be used with touchpad and left and right keys. I do have original motherboard, i will be taking the original connectors off because they are both ribbon cables. I know they are very small to solder, just a bit of practice I should be able to get wires joined to connectors.

You're welcome.  I have never explored reusing a touchpad, but your query got me interested in looking into it.  There is an instructable showing someone has turned an old HP touchpad into a PS/2 mouse at Turn a Trackpad From a Broken Laptop into a PS/2 Mouse and based on the comments it appears that you might be able to turn it into a USB connected device (depends on the touchpad).