OS X won't boot

[wayne rankin]

Hi - I had to switch startup disk to OS 9.2(.whatever is latest) in 
order to run Quicktax and when I try to get back into OS X via OS 9's 
startup disk control panel, OS X does not appear as a choice. Ran 
TechTool Pro (latest version for OS 9) but I think that only made 
things worse - now the entire computer is write-protected so I can't 
even clean it up by treating it as a Firewire drive and using 
DiskUtility from another computer running OS X.

Any suggestions before I erase the disk and reformat?

terry
Sarnia ON