2. Clear the "Cache" and "Data" for the launcher. Now remember this will remove any saved settings and info in regard to the launcher. Just like it would for any app.
3. Try installing a different launcher. You can find quite a few on the Google Play Store.
4. If nothing else resolves this, then you may well have to "Hard Reset" the device. But save that as a last option as it will wipe the phone completely and restore it to its original state. This means you will have to save all of your personal data, info, files, etc. somewhere off the phone and restore it all after the reset. On top of this, all apps you have added would be wiped and you would have to reinstall them again.