In most cases, the handset will not turn on because the battery is flat.
Step 1: Refer to the manual for instructions on how to turn the handset on. If you have a handset and you usually don't let the battery run out before you charge it but this has happened in this instance, charging the handset will not turn the handset back on. You will need to manually turn the handset on.
Step 2: Connect the handset into the power socket. After plugging the handset into the power socket a battery will appear on the screen for a short time (this may take a few minutes depending on how flat the battery is.) Leave the handset on the charger for a few hours.
Step 3: Turn the phone on. If the battery icon does not appear within 10 minutes, if possible, test an alternate charger as the issue may be with the charger and not the handset.