Can I change the locks if they have gone?
No. Abandonment has its own procedure in almost every state, with a notice and a storage period, and getting it wrong is a separate claim with its own damages. It is the most common way a landlord who has won still loses money.
From the guide When Rent Has Failed: Navigating an Eviction.
The one thing that matters most
Do not change the locks, remove anybody’s belongings, shut off a utility, remove a door or a window, or threaten to. Self-help eviction is unlawful in every state. It converts a case you would probably win into one you will certainly lose, and it exposes you to damages, penalties and in several states criminal liability — often several times the rent you are owed. Seayora will not help with it and does not record it. That warning is on every eviction screen and it cannot be dismissed.
Read the whole guide: When Rent Has Failed: Navigating an Eviction