Hi. To fix "launcher has stopped working" error you must hard reset your phone. This will remove the launcher and install the factory default launcher.
To hard reset your phone follow the instructions below.
1. Switch off your phone
2. Press and hold volume up then then power button. This will take you to recovery menu. If your phone boot normally, switch it off again and try volume down + power button.
3. From the recovery menu scroll down to "wipe data/factory reset" using the volume down button press enter using power button.
4. Now scroll down to "yes" and tap power button to select
5. Done, select reboot system.