lobolance

My media tv died a couple of days ago (insert cranky here; half hour on hold with Costco, and now Vizio says leave a message... and it's a year out of warranty, but only just short of 4 years old). 

The computer attached to it logically enough is the  machine I use for itunes, photos, etc. I had it set up for two monitors, with the main display on the big tv. The computer itself doesn't really show anything (since it's last wipe and redo a couple months ago). So, I can't see anything on its monitor, so I can't make it a one monitor display again. Maybe there's some way to do that through one of the boot up sequences? F8? F11? Any one know?

Thanks in advance.