It would be good to have a little more information. Do you have any more of the original wood. If you do are the pieces you have exactly the size of the pieces you want to replace. Do you know if the floor is nailed or glued down and what is the subfloor. Replacement may be a little time consuming but it will not require any special tools. Basically, using a circular saw, you need to cut (not quite as deep as the replacement board but very close)the damaged piece out from the corners in at a 45 degee angle and cut the center out as a rectangular box. After you have cut it out you will pry out the center section and tap out the damaged piece from all 4 edges so as not to damage the tongue and groove of the pieces surrounding the damaged piece. Generally once the board is out and you have cleaned around the existing tongue and groove you can cut the bottom half of the groove and glue the new piece in place. Hope this helps and be sure to ask if you need more specific info.