A detailed description of this procedure is found in the manual of your watch. You can find the right manual with the module nr. on the back of your watch (4 digit number in a rectangle)
The manual for your watch can be downloaded via the link provided below:
Timepieces Watches
If that's from the very start when you bought it, it might a factory defect and you cannot do anything about it. That is already considered a junk. Buy another one.
Hold A (about 10 o'clock position) button down until display flashes
then use D button (about 5 o'clock position) to cycle through the Time Zones until you get to the one you want
A detailed description of this procedure is found in the manual of your watch. You can find the right manual with the module nr. on the back of your watch (4 digit number in a rectangle)
The manual for your watch can be downloaded via the link provided below:
Timepieces Watches
Before buying myself a watch, for a long time I was choosing user manuals from my catalog http://manymanuals.com , you can also see information about different Cassio models
probably needs a new battery,cr2016 should be, see videos on youtube on how to replace.What I found was connecting the AC pin to the top of the battery,which is the posive resets the watch after new battery in
from the user manual press the button closest to the seconds display on watch . bottom right button in normal time display to switch between am / pm time or 24 hundred military time.
http://mygshock.com/casio-manual/548/
enlarge the internet browser display to read which button to press to change the time or date.
press button B top left button to go into change mode
press button C bottom left button to move to seconds or minutes or hours .
press button A bottom right button to advance the time
press button b top left button to go back to normal time display
If the digital display still works, there is most likely something wrong with the watch movement. If there is no readout at all, the battery is probably dead. In both cases you should take your watch to a service centre to have it checked.