My macbook pro won't start up and touchpad not working.

It is looking for an external mouse and trackpad.

Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

Try resetting the  SMC  https://support.apple.com/en-us/HT201295

erin_marie2488 wrote:

It's asking me to toggle a switch on for a mouse but do not use a mouse... only my touchpad. Any suggestions?

If your Mac doesn't turn on

https://support.apple.com/en-us/HT204267

If your Mac doesn't start up all the way

https://support.apple.com/en-us/HT204156