Welcome to LQ.
Would you mind posting what distro you are using ? Are you sure you didn't change anything before this happened.
As laptop touchpads usually use the psmouse module, and assuming that it is built as a module you can try running this as root to make it work:
# or if that doesn't work, run
Also, you would run these command in a terminal or console such as rxvt or konsole. To log in to root type
then put in your root password. Some distros, notably Ubuntu, use 'sudo' instead of 'su', so you would use that to run it.