What should you do if your best friend won't talk to you?

Say that your sorry in a polite way (if he/she is angry about something that you did), point out you faults (always works!). You MUST swallow your pride

another thing that might work is let him/her in on a secret the he/she Will feel like a best friend to you (usually best friends let each other in on secrets) remember he/she isn't happy that he/she isn't talking to you, he/she just wont swallow his/her pride a give in. if YOU could give in and say "I was wrong, lets end this" then he/she will see the you are truly his/her best friend and also it will show that you are not a coward to giving in.