I"m not a lawyer, but in some states you can get triple damages. In other words 3 times the amount of the check.
Since you have already called her 2 times and left messages...did you give her a time frame to call you back by?
Your next step is to send her a letter. I would send her a Certified, signature required letter explaining your situation ( research what you're options are) let her know what legal recourse you have and give her a deadline, find out how long need to give her legally.
Don't let this customer get away with this. I have seen people post "bad" checks in their stores..lol
Things happen, and they happen to EVERYONE, but...if she's ignoring you...it takes on a "WHOLE" other meaning!
Sorry that you have to deal with this.