Or just order it online from Apple -
here.
"Assuming" you have a backup, you might be willing to give
this hint a try - same link TM has above.
That hint was for Snow Leopard (which introduced the time stamp naming of screen shots) and how to go back to the previous "Screen Capture 1" format.
You might try that in reverse.
Of course it may totally screw it up - I don't know as I don't have any bootable Tiger drives around to test it.
Although, if you have an Intel Mac, you really should get upgraded to Snow Leopard at a minimum.