Imoutodesu: I have no such file in my Blood directory.
I did a clean install though, I guess this file gets created on first succesful start.
kexengine.cfg is found in:
C:\Users\<Your Username>\AppData\Roaming\Nightdive Studios\Blood EX
Even uninstalling shouldn't remove that file. As said above try deleting that and it should reset all options back to default.
(As it will have to re-create the file, you will have to re-bind any keys you changed and change any other options again though.)
Edit:
dr.krajzega: +1
Cannot load any saved game. I've uninstalled the game, deleted whole Nightdive Studios folder from appdata and reinstalled the game - no luck.
On the main menu bring down the console and type
developer 1. Then load your saved game. Save it again (replacing the save.) Then bring down the console again and type
developer 0.
That save should work. If you have more than one save then repeat loading and saving just remember to turn off developer mode when you are done.