Many users tend to use a mouse on their laptop because it’s more comfortable for them, but sometimes certain problems can occur when you connect a mouse to your laptop.
When you plug the mouse into the USB port, the touchpad stops working.The reason for this is that some laptops have a feature that automatically disables the touchpad when you connect an external mouse
Solution to Touchpad Not Working When Mouse Is Plugged in
Open up Windows Settings by clicking the “Start” button, then clicking on the cog wheel. You can also hit Windows+I.
Click on Devices option.
On the Devices page, Click on “Touchpad” category on the left and Under Touchpad check “Leave touchpad on when a mouse is connected“.
Alternative Method
Open Settings, and click on the Devices icon.
Tap on the “Mouse” option from the left-hand side. And click Additional mouse options.
Depending on what brand of laptop you have the next steps could differ slightly, but you should be able to find the option in there somewhere.
Switch to Device Settings tab then check “Disable internal pointing device when the external USB pointing device is attached” option.
That’s all.