Does the walkie talkie still power on? If it does, take a picture of the display with something displayed on it. It could be a simple character display or 7-segment display. If you can still power it, it will be easy to tell.
It probably is not possible to try to display things on the display while it is still installed in and connected to the walkie-talkie electronics.It would be difficult (or impossible) to operate the walkie-talkie without the display.It does not appear that you can display arbitrary letters on that display. It looks like it is custom-made to display only a few things related to the walkie-talkie operation. At best, you could display different digits where it shows channel number, etc.