Resetting a Lost ScreenMode

[JaXanim]

Could someone remind me, it's been a few years now. The last time I shut down my Amiga (OS3.9) I'd been messing with the screen modes and saved one I can't run on my current monitor. I need to reset the ScreenMode so I can run my Amiga again.

I have an Emergency Boot disk which allows me to boot up and run with a television screen. I can get into the Workbench: partition and locate the ScreenMode icon in the Prefs drawer.

I have been into Workbench:Prefs/Envarc/Sys and renamed the existing screenmode.prefs icon so it can't use that on bootup. However, I can't open the ScreenMode icon in Workbench:Prefs to select the correct mode. The icon is the 'wrong type'. I'm obviously doing something wrong and i'm sure someone here will put me right.

Many thanks, JaX

[JaXanim]

I think I confused things a little. When I try to open the ScreenMode icon, nothing happens. There's no response. I got the 'Wrong Type' message when I tried to open the icon using Ed the script editor. I couldn't remember whether you changed ScreenMode stuff using Ed or what.
Many of the icons in Workbench give no response when double-clicked. Is this because I've booted from the Emergency floppy?
At present I have a VooDoo graphics card running on a Mediator. The Devs/Monitors drawer contains only VooDoo and the low frequency drivers, PAL and NTSC I think. I'm pretty sure I only need to set the correct ScreenMode to get output to my TFT monitor. It was running on a TFT before I messed it up. All advice welcome.

JaX

[JaXanim]

@motorollin

I renamed the screenmode.prefs file in Envarc but I can't open ScreenMode in Workbench:Prefs to set the correct driver.

JaX

[JaXanim]

OK many thanks for everyone's suggestions. I will check them out and report back later.

JaX