Troubleshooting Tips (& manual install procedure)As describe better in the above topic, if you start a new game, cheat to level the character up, run to the Dark Forest, get the quest and go to the stalker cave, that will help determine if the problem is with the game itself, or in the save game folder.
Alternately, if you have access to a different computer, you could try your save game there.
You can also just get the silver armour by downloading the inventory files;
Lost Items - guide and directory of inventory filesor get into the easter egg area by;
Teleporting Anywhere, via hex editor