A mortgage may provide the mortgagee with the right to prevent "waste" to the security of the loan (the property). The right to posession to the real property is yours until the actaul foreclosure and issuance of a certificate of title or until there is a court order providing posession or abandonment by the mortgagor. If your lender has changed the locks you normally are provided a contact number by the persons changing the lock you should contact them if the property has not been abandoned. You also should contact your lender to advise that the property has not been abandoned. If neither is sucussful you should notify the court of the lender's action and request posession of the property be returned to you.
This situation is complex and no legal opinion can be expressed concerning the outcome of any litigation or planning without a full consideration of the facts and legal research. This answer is given solely as general information and is not a substitute for a legal consultation, nor does it create an attorney-client relationship between you and either the writer or his law firm.
While it is possible for a lender to do this, we often see that the loans were invalid or transferred invalidly and as such they do not have this right. You should review your loan and situation with a Florida Foreclosure Lawyer to see what your options are.