How long does a previous landlord have to return deposit?

I moved out of my previous residence on April 26th also the last day of the lease. Turned in keys and also requested a move out walk-through inspection with somebody from the office staff. Still have not heard back from previous landlord and nothing inmail email or phone call returned as far as deposit goes. Even during this pandemic how long does a landlord have to return deposit or notify you of any charges. And if it's past what's the best way to approach landlord via email or certified letter to request the deposit or double deposit or however it may work in the state of Washington.