Reduce the water level so it can right itself. Add decor or plants to get it upright if needed. Add some Epsom salt at 1 tbsp per 5g. Add some kanamycin and keep the water pristine. Cross fingers!
Make sure you add Epsom salt/ Magnesium Sulfate, unscented, USP. You can get it at Target. This is different from Aquarium salt, and it will work as a laxative to help release any air bubbles/waste that could be causing the swim bladder.