I have a 2007 Acura TL, recently I changed the battery. After battery change I tried to enter security code into stereo and discovered that one of my number buttons is broken preventing the code form being entered. Is there anything I can do?

 

I'd try some compressed air into the space around the button. Then if that doesn't work, I'd probably try some electrical contact cleaner. Either method, I'd press the button a ton of times afterwards. Might be able to convince it to work. Worth a shot, since it's already broken.

 

I was able to get the number entered by pressing many times. Now that the number is entered is there a way for me to change the code so I don't need the number that doesn't work?

 

^
I don't think so, but I could be wrong.
You got the button to work, so why don't you just clean it out so it operates smoothly for next time?