No LCD Display since battery low and pho...

The phone started bleeping as low battery. As was middle of night simply switched phone off. The next day, when put back in its charger and switched back on, no display whatsoever showing - but back light still worked (as did making and receiving calls - although this no use when display not working as you can't see who you're dialling, nor who is phoning you). Problem is how to get display to reappear.