FAILURE TO TURN OVER OR START

-SECOND HAND FALCON SEDAN.
-NO REPLACEMENTS OR REMOVALS. BESIDES RADIATOR, BONNET & FRONT-GUARD.
-WAS A GOVERNMENT CAR, INVOLVED IN A MINOR INCIDENT.
Which involved the replacement of the *ABOVE.
-DASH LIGHTS ARE RESPONSIVE, ALONG WITH A/C.
-'CODE' KEEPS SHOWING ON CD/RADIO.
WE HAVE THE CODE, BUT WE'RE UNSURE ON HOW TO PUT THE CODE IN, AND CORRECTLY AT THAT. AUDIO SECURITY CODE IS: 9023.
-CHECKED THE CD/RADIO WIRING AND THEY'VE SHOWN VERY LITTLE CORROSION/RUST.
WIRING ALL CORRECTLY POSITIONED.
-BATTERY IS BRAND NEW/FULLY CHARGED.
-CHECKED/CHECKING THE FUSES - IN & OUT OF CAR.
-GOT BOTH KEYS.

QUESTIONS:
- Because the car was involved in a minor accident, is it still possible to jolt the wiring out of it's correct positioning?
- How do I put my Audio Code into my CD/RADIO, when it only has 6 buttons. And how do I place the numbers 0 & 9 in?