Use the Early Startup Menu by pressing both mouse buttons when booting and select "Boot with no startup sequence".
That will get you to a CLI prompt.
From there you can either manually check your Monitors directory under devs to see if you have anything other than the PIV monitor drivers or use "run :nil> LoadWB" (without quotes).
That will give you a basic Workbench with no drivers loaded and it's behind the CLI shell.
If not, just copy over your monitor drivers that work with your monitor, possibly PAL, from your Storage floppy.
Delete the PIV monitor driver in that DEVS/Monitors directory.
Reboot and you should at least get an error you can see and will be able to see your Workbench.