Here are some things that have helped for us:
Opening windows will really help!
keep the dehumidifier on constantly. If you have any mold on the walls, the dehumidifier needs to run consistently. You will see the moldy smell will disappear. It may take months for the smell to dissipate but it should work. AND keeping water out!! You might have to fix any issues with your gutters and adding some drainage tiles in your yard underground to carry water away from your house so you don't get any flood waters coming in which will give all the musty moldy smells.
We use these rocks for getting rid of odors: https://chemistrycachet.com/most-effective-way-to-eliminate-pet-odor/
Wash everything from ceiling to floor with TSP or a vinegar water solution. Have carpets, drapes, upholstered furniture cleaned as they harbor odors. If you live in a humid climate, consider a dehumidifier.