A good innerspring mattress should be sent to a commercial renovating company.
Renovation is too difficult to do at home.
Ask about the cost of such work. It could be less expensive to buy a good reconditioned or new mattress. If mattress must be used temporarily, scrape off surface dirt and expose it to sunlight to dry as much as possible. Cover mattress with a rubber sheet before using it. If you decide to keep any flood-soiled mattress, it should be sterilized.