That's a tough one. Was the leak in the interior of the vehicle and is there evidence that it got into the monitor? (Visible moisture in the display?) The radio is actually the "brains" of the whole info-tainment system. It's possible that only the radio is damaged but it controls the display of GPS, phone, music, etc. You could try the easiest fix which is to do a hard reset of the system. Disconnect the battery for 15 minutes or so. Then reconnect and start the vehicle. You will have to reset settings like clock, language , etc. from the front display for speed and RPM and if successful, the settings that you had for radio.
If that doesn't work then you're probably going to have to take it to a shop for diagnose/repair. The radio is a separate item in the info-tainment package and will be about $1,000 to replace. Good luck.
