MONITOR SET TO WRONG RESOLUTION WHICH WILL NOT DISPLAY SO SWITCHES TO A BLANK SCREEN

[Max1910]

i KNOW WHAT IS WRONG AND HOW TO FIX IT BUT THAT IS NOT THE PROBLEM.  WHEN i CHANGED A SETTINNG ON A MONITOR TO THE RECOMMENDED SETTING IT WOULD NOT DISPLAY IT AND SO SWITCHED TO A BLANK SCREEN.  TO FIX IT i MERELY NEEDED TO SWITCH BACK TO THE PREVIOUS SETTING, BUT i COULD NOT DO THAT BECAUSE THE MONITOR WOULD NO LONGER DISPLAY.  So I changed the monitor for one which accepted the new resolution setting.  Now I have changed the monitor again as that one failed for differeht reasons.  This is a widescreen one and it displays two black bars either side of the wider screen.  I think this can be fixed by changing the settings - to the recommended ones.  However, if I do that and this monitor does not support them then I have the same problem again so needing yet another monitor.  So I cannot go through the vArious processes to remove the black bars in case my screen goes blank and then I have no way to fix anything without yet another monitor which will display the settings.  So much advice absurdly suggests how to correct settings but forgets that if the monitor stops displaying you cannot see anything in order to correct it.  Is there another way to correct the settings rather than keep buying monitors please?