Boot from SD and edit screen res on native OS?

[dhosh]

I played around with a Mangaro image on SD and all was well.  Tried changing don't size for these poor old eyes and worked.  Also found screen resolution change option.  So... I booted back up on the default internal image and tried the same.  Found both settings.  I set the screen resolution ton1024x768, as was the next visually larger size... Set to system wide and applied then rebooted.  Now, after logging in (with larger fomt on login window).... It boots to a blank screen.  No curaer, not mouse pointer.  It occasionally does a light flash, like it's trying a different resolution, but now change.  I don't have a USB to HDMI adaptor, so am stuck.

I can still boot to Mangaro, however.  can iount the internal drive, and change a config file to get back to theddefault resolution1292x1080?

Thanks in advance
Dennis