Then restart your Mac once again to return to normal mode. Once in safe mode, see if your cursor is working. Keep holding it till you see the login screen.
When you hear the startup sound, press and hold the Shift key. To restart your Mac, turn it off and on again. That way you can find out if there are any third-party apps causing this to happen. However, if your mouse still keeps disappearing on your Mac, you might want to take it further and restart your computer in safe mode. Sometimes simply restarting your Mac can help you save the problem and bring the mouse back. Keep holding the keys till you hear your Mac restart again. When you hear the startup sound, press Command (Cmd) + Option (Alt) + P + R. To reset NVRAM, first, switch your computer off and on again. It can also help you fix your disappearing cursor problem.
NVRAM is responsible for storing data and computer settings if the power is switched off. Resetting NVRAM is a common thing to try when troubleshooting your Mac. If your mouse doesn’t reappear then, try force quitting an app that you think might be causing the problem. To do that, press Command (Cmd) + Option (Alt) + Escape (Esc). When your cursor disappears, bring up the Force Quit menu and see if that fixes the problem.