Over-riding Screen resolution?

[Gryffon300]

Now, you're going to have a chuckle at my expense, and that's OK, but can some IT guru give me some help? (There's no [grovel] smilie, or I'd use it now.)
OK, here is my problem. I've effectively locked myself out of SH4 as follows. I use a laptop with a screen res of 1366x768 (16:9). BUT, I have been playing on an external monitor with a screen res of 1680x1050 (16:10). This is the in-game graphics option setting that I have selected. No problems, UNTIL the monitor was taken to another location.

Now, trying to open and play on the laptop, the screen only displays the top left-hand 80% or so of the game. Now, that's ALMOST manageable, because I can go to the Options - Graphics Settings and re-set the Screen Resolution and Refresh Rate BUT, and here's the rub, I can not 'Apply' the setting, because the button is off the screen at the bottom right, and can't be accessed.

So, is there a way to go into the game folder and manually re-set the screen res?

Thanks

Gryff