My casio G Shock has a blank screen and is only flashing C in the upper right corner

"G-Shock WR20BAR" could mean hundreds of different G-Shock models. If yours is an all digital G-Shock, the answer is fairly simple. When looking at the watch face, the upper left corner button is the "ADJUST" button. Press and hold the ADJUST button for a couple of seconds. You should start to see something flash on the display. Some models will have many options to select in ADJUST mode. To scroll through them, press the MODE button, which is in the lower left corner. You set the hour, minute, seconds, month, date, and year each separately. When you are done, press the ADJUST button again and you'll be back to normal time keeping.

If you want to learn more about your G-Shock, there is something called a "MODULE" inside it that is the brains of the watch. You can find that on the back of the watch, outlined in a rectangle. Usually a 4 digit number. You can download the manual for your watch using that number, if you enter it on a CASIO website:
http://support.casio.com/en/manual/manuallist.php?cid=009

for people who don't want to do the trouble of looking on the casio webpage here are the steps:
Go to Alm or alarm
press the button in the lower right-hand corner twice
then press the button in the upper left-hand corner to toggle the hourly alarm on an off (it says on or off in the mid top)
here's a link to the casio webpage if u don't understand me http://support.casio.com/storage/en/manual/pdf/EN/009/qw3285.pdf

An example for G-shock: I searched for casio g-shock manual and got this: http://world.casio.com/wat/download/en/manual/

You enter model from back of watch and it gives you a searchable PDF manual.

For mine, model 2638 (and likely most G-shocks), you press and hold the upper left (Adjust) button until the City Code flashes. You then press the lower left (Mode) to enter DST mode then press the lower right (Receive) as it cycles through On, Off and Auto.
On moves 1 hour forward, Off moves 1 hour back. After you select, you press the upper left button (Adjust) twice and it's set. I would not pick Auto anymore as my watch is still set to the original DST days which were changed in the US years ago and no longer match, I don't believe the DST days used can be changed by the user and I don't believe Auto receive adjusts for DST.

Rem is the reminder function of the watch , you can turn it off and on by holding down the bottom right button usually on casio watches. You can also find the online manual here http://world.casio.com/wat/download/en/manual/


please rate solution

http://www.casiosalesandservice.com/repair.htm

Setting the Time
1. G-Shock watches feature a digital display that is set using the function buttons on the outside of the watch face. To set the time, press and hold the the upper left button until the seconds unit blinks on the display. Reset the seconds to "00" by pressing the lower right button.
   
   Push the lower left button to switch to the hours unit, which will start blinking. Advance the hour by pressing the lower right button. If you hold down the lower right button, it will advance the hour unit at a higher rate of speed. Once the hour is set, press the lower left button to switch to the minutes unit. As with the hours unit, pressing the lower right button will advance the minutes and holding it down will advance the minutes rapidly.
   
   Once the time is set, press the upper left button to save the setting.
Backlight
2. The backlight on a G-Shock watch has a manual control and an automatic function that will light the face of the watch whenever the alarm, countdown alarm or hourly alarm ring. To use the manual backlight, press the button on the bottom of timepiece. The light will glow for approximately 2 seconds before going out.
   
   The automatic function is set by pressing and holding the lower right button. When the automatic function is set, an indicator icon will display on the watch face above the seconds unit. You can turn off the automatic backlight function by pressing and holding the lower right button until the icon disappears.
   
   Note that backlight causes a drain on the battery, and overuse of the backlight will greatly reduce battery life.
Setting the Alarm
3. The G-Shock has an alarm that emits an audible tone for approximately 20 seconds when it turns on. To set the alarm, press the lower left button until "AL" displays in the upper left corner of the timepiece. Press and hold the upper left button until the hours unit starts to blink. Adjust the hour by pressing the lower right button. As when setting the time, you can advance the hour at a higher rate of speed by holding down the lower right button.
   
   Once the hour unit is set, press the lower left button to advance to the minutes. Use the lower right button to set the minutes. Follow these same instructions to set the month and day you want the alarm set.
   
   When the alarm time and date are entered, press the upper left button to save the setting. Push the lower left button three times to return the G-Shock to "Timekeeping" mode.

if there is a black screen and shows chg thats mean your battery level is to low ////// so you must charge as soon a possible,,,,,,

if this is the same as my watch, it's solar powered and when it gets TOO LOW< it will blank out and begin to charge .  Stick it in direct sunlight for a day if you can.  You can also stick it under a regualr lamp, but it will never get fully charged, but it should be enough to operate at least.  The battery meter is the top middle dial on the face.

hold b which is the button on the top right corner until it says AUTOEL in the in the top right corner of the screen

http://world.casio.com/wat/download/en/manual/

try for the manual from here.



riz.