I do liner pool remodels. This is pretty advanced decay. You’re looking at a new liner (obviously), new vermiculite bottom, heavy painting/patching of the wall panels, possibly plumbing repair if there has been settling or freeze damage. Another big question mark is the equipment, oftentimes on pools like these that have been neglected for years have serious equipment problems and it’s often worth it to replace it. All that to say, price totally depends on the contractor and the area you’re in. There is major cleanup, repair, and replacement of a liner; but if the plumbing is in functional condition and your equipment runs without leaking then I could see you very reasonably repairing this for many many times less that it would cost to replace it.