Resetting external monitor display settings to default

I have a small, older(ish) Sansui TV that I use as an external display to my macbook air via a thunderbolt to VGA adapter.

Recently, I tried to use the monitor unmirrored, and selected a resolution that normally displays perfectly when I am mirroring. I lost the signal, and the TV told me that it was unsupported. Unfortunately, I tried to revert the selection, but nothing worked. I've even tried tweaking the ColorSync profile for it, to no avail. Now, I can't even choose another resolution because I can't even see what is on that part of the screen.

I know I'm better off with a newer display that doesn't require VGA, but is there a way to reset/restore the settings?