[Total Home Care]

only advice i can give is you must first find out how much water damage has been done by taking out a small section of the bottom of the sink base on the inside under sink.....but if their is floor damage under the sink base you will need to take out the complete unit and repair floor as needed.
''''''''''''''''''''''''''''with the limited info you posted i am only speculating that the base is rotted from the water damage....only then should you consider cutting out a small section of the floor base of cabinet to inspect the actall floor under and that is only if you cannot view this from a basement or craw space......;;'''''''''''''''''''''''''''''''''''