Why wont my radio woek after being jump started

I'm assuming that your vehicle was jump started due to it's battery being depleted. In such a case it is normal for any stereos with start codes to require a four digit PIN to be punched in before operation can commence. In the case that your stereo doesn't require a PIN and doesn't ask for one, then it is possible that your stereo's fuse may be blown or in fact that your stereo is faulty and may be the reason for your power drain.
It will help if you can provide more specifics such as whether or not your stereo shows any illumination lights or screen prompts etc. Perhaps it's on the radio setting, but all you're hearing is static. Please provide more info if possible.