does the radio itself still work, and the remote display is out? Those sony remotes were pretty tough - it might be as simple as a popped fuse if the whole radio is out (the head unit is in the helm behind the door) - or there's direct replacements available for cheap on eBay.
For the depth + GPS, you probably have a Garmin of some sort... there are replacements that might still be able to use the existing transducer, which would be easiest, or if your boat is open underneath (no under-skinning) it's pretty simple to run the new units. Not too bad to DIY.