Try this:
1) Boot from a workbench floppy disk. You should now be able to see all the drives on your desktop.
2) Navigate to the hard drive on which your system is installed. Go to prefs/env-archive/sys/ drawer
3) Rename workbench.prefs to old_workbench.prefs
4) Remove the floppy drive and reboot form the hard drive (perform a cold reboot by switching off, waiting 30 seconds, then switching back on).
Should be back to default.
Regards
Rich
PS Don't panic (Mr Mannering!). God, I hate Dad's army, but its influence is ubiquitous in British humour. :-P
