Have you checked in device manager to see if the touchpad appears there and/or there are any problems with drivers and stuff?  Have you check if touchpad is enabled in device manager? If there is/are any problems, you will see an exclamation mark next to it and some yellow or red warning.  If you want to check, you can do the following:

– log in with an administrator account
– click on windows key + Pause/Break key at same time
– click on device manager
– scroll down to mice and other pointing devices
– click on the + sign to expand it
– highlight on entry and then right click
– select properties and check under general tab for any problems.  If there is any problem it should tell you so in the box at bottom.  If there is a code, make sure to record it and then research it or post it here. 
– on menu, click on the driver tab
– select update drivers and if there is any, make sure to update it
– close device manager and then restart computer
– try to see if it works
– if it doesn’t, follow the same steps and instead of selected update drivers, select uninstall and restart computer
– if you are running windows 7, it will install a generic driver
– see if it works

Is there any software like Alps or synaptics installed?  Make sure software is up to date, if not just download the most recent version.