One way that laptops remain portable is because of the way the hardware is designed. Most laptops contain every component that a desktop does but in a much smaller package. This also applies to the touchpad (also known as a trackpad) on a laptop, which is basically a mouse replacement. In order for the touchpad to work, the drivers for it must be installed. Drivers aren't always enough because there are other conflicts that will prevent the touchpad from working.
Click the "Start" button and type "Main.cpl" in the box. Press Enter.
Go to the "Device Settings" tab and click the box by "Disable internal pointing device when external USB pointing device is attached" to clear it.
Click "Apply" or "OK" to exit. If you have upgraded to Windows 7, this setting is reset by the upgrade that caused the touchpad to be disabled.
Type "Uninstall" in the start menu and select "Uninstall a program" from the list. It will be listed under "Control Panel."
Look for "Synaptics Pointing Device Driver" and click "Uninstall." The actual term may vary depending on the manufacturer.
Go to the website for the manufacturer of the laptop and download the most recent Synaptics driver based on the date it was posted. There are generic drivers from Synaptics that will restore functionality if you cannot download from the manufacturer.
Apply a small amount of ammonia-based glass cleaner to a piece of cloth.
Wipe the touchpad gently to clear it of dirt and grime. Do not use an excessive amount of liquid or it will get inside and possibly damage the touch pad.
Wait for it to dry and check to see if the problem continues. This process usually stops the pointer from jumping erratically across the screen. If it does not, update the driver as described in "Update the Drivers."
The generic drivers will get the touch pad working but will likely remove the customisation options enabled from the manufacturer.