OK, so I buggered up the SP.. how to get it back ?

[Spigalau]

Was playing in the Sandbox, it crashed and now I can't run it back up in SP mode anymore.

I can open it back up in the SandBox and the main island ground texture is now a rather bright white (almost snow) and the chickens can walk around under water...

So how does one fix it up ? Is it a re-install or is there a roll-back ?

[Plasma]

uninstall and reinstall.
Ive had to do it a few times after screwing up the map.