IMPORTANT: If model-specific information is required to complete any of the steps in this solution, refer to the operating instructions supplied with the product. If you have an older model that does not connect via USB, the steps that mention USB connection will not apply.
Note: Because each of these steps represents a possible solution to this issue, check the device status after completing each step.
Determine which of the following conditions applies to your model, and try the corresponding solution.
The battery charges properly if your device displays a battery indicator. Wait until the indicator changes to FULL for the battery to charge completely.
Your device will display a black screen if you haven't used it for a long period of time or the battery was drained. Charge the battery for about 5-10 minutes before you operate the Walkman.
If the computer enters a power saving mode while the player is connected via the USB cable, such as the Sleep or Hibernation mode, the battery will not be charged. Instead, the player will continue to draw power from the battery, discharging it.
Make sure the USB cable is plugged into the player and the computer securely. Unplug the cable from both ends and plug it back in.
Connect the Walkman using the supplied USB cable.
Do not use a USB hub. Connect the Walkman directly.
Try a different USB port on the computer to make sure there's no problem with the current USB port.
Try to charge a different device to make sure there's no problem with the computer.
If your unit has a built-in battery switch, verify that it is in the ON position.
If the battery still won't charge and it is replaceable, try a new battery.  Go to Parts and Accessories. 
If using an AC power adapter, make sure the adapter is securely connected and plugged into a working AC wall outlet.
Try plugging the AC power adapter into a separate AC wall outlet to make sure there is not a problem with the current AC outlet.
Connect the Walkman using the supplied cable.
Try charging with another device to check if there is a problem with your AC adapter.
If the battery still won't charge and it is replaceable, try a new battery.  Go to Parts and Accessories. 
If the battery isn't replaceable, repair may be required.  Go to Product Repair. 
Notes:
Charge the battery in an ambient temperature of between 5 ºC to 35 ºC (41 ºF to 95 ºF). If you try to charge the battery outside of this temperature range, the battery indicator may blink, and charging cannot be performed.
The number of times a battery can be recharged before it needs to be replaced is approximately 500 times.
This number may vary slightly, depending on the conditions under which you use the player. If you do not intend to use the player for over six months, charge the battery at least once during this time to maintain battery performance.
If the computer enters a power saving mode while the player is connected via the USB cable, such as the Sleep or Hibernation mode, the battery will not be charged. Instead, the player will continue to draw power from the battery, discharging it.
Make sure the USB cable is plugged into the player and the computer securely. Unplug the cable from both ends and plug it back in.
Connect the Walkman using the supplied USB cable.
Do not use a USB hub. Connect the Walkman directly.
If your computer has more than one USB port, try plugging the USB adapter into a different USB port to make sure there is not a problem with the current USB port.
Try charging with another device to check if there is a problem with your computer.
If using an AC power adapter, ensure the adapter is securely connected and plugged into a working AC wall outlet.
Try plugging the AC power adapter into a separate AC wall outlet to make sure there is not a problem with the current AC outlet.
Connect the Walkman using the supplied cable.
Try charging with another device to check if there is a problem with your AC adapter.
Notes:
Charge the battery in an ambient temperature of between 5 ºC to 35 ºC (41 ºF to 95 ºF). If you try to charge the battery outside of this temperature range, the battery indicator may blink, and charging cannot be performed.
The number of times a battery can be recharged before it needs to be replaced is approximately 500 times.
This number may vary slightly, depending on the conditions under which you use the player. If you do not intend to use the player for over six months, charge the battery at least once during this time to maintain battery performance.
Check the terminals of the Walkman
If the terminals are not connected to each other properly, the Walkman may not be able to charge. Please make sure to keep the Walkman terminals clean.
For waterproof Walkman model, wet a soft brush such as toothbrush with water and wipe the moisture off, for details check the following video: