Monitor not showing anything

[John Public]

I have a Samsung LE23R86BC which according to specs can handle 1368x768
So I edited /boot/config.txt to have
hdmi_group=2
hdmi_mode=39

Now when I boot RPi my monitor says "Mode not supported" and a blank screen. However, the lights blinking on RPi indicate that it has booted.
Is there a key combo or something that I could use to set the resolution to a default so I can fix my monitor settings on /boot/config.txt?

[fruitoftheloom]

I have a Samsung LE23R86BC which according to specs can handle 1368x768
So I edited /boot/config.txt to have
hdmi_group=2
hdmi_mode=39

Now when I boot RPi my monitor says "Mode not supported" and a blank screen. However, the lights blinking on RPi indicate that it has booted.
Is there a key combo or something that I could use to set the resolution to a default so I can fix my monitor settings on /boot/config.txt?

If you are using the TV HDMi Input and a known good HDMi cable the resolution should be auto-detected as it is a 720p Screen:

http://www.backoffice.be/prod_uk/Samsun ... n_720p.asp

[John Public]

Thanks for the reply. I managed to get the setting back to normal this way:
- I hard-shutdown rpi (pulled the power cord)
- took the SD card to another Windows computer and edited the config.txt to a better value.
It started OK with no data loss, Whew!