A post like this comes up every Spring. The floor is not glued down and as the temp changes it expands and contracts. It is fastened down under all the cabinets etc. It is put in place then the interior is built over it. Very inexpensive to repair. Self stick tiles will not stay in place. Cut the old sheet out around all the cabinets etc. Use it for a pattern on the new material. Lay it in place and hold it down around the edges with 1/4 round. Done. I would replace it and try to get the most out of your trade you can get.
B.O.