If your Thosiba laptop running under Windows 10, go to Settings > Devices > Mouse & Touchpad and make sure that Leave touchpad on when a mouse is connected is checked.
You can also try these steps to fix the touchpad on Windows 10.
If the problem persists, reinstall the touchpad driver from the Device Manager by right-clicking on it and choosing Uninstall. Then restart your laptop.
These instructions should be the same or similar with Windows 7 and 8. For "Settings", go to the Control Panel.