If you ran the bill and approved it you might have a reprint bill image. This will depend on how you printed the bill and what version you are running. This can be found under bills - reprint bills.

If you clicked somewhere else the bill might be in proof or revision stage. In that case bills - approve or clear will show you the bill. Or you might have cancelled in which case the slips are not marked billed and you have to restart.

You can look at Billing Assistant for the matter and see the current status and what is waiting to be billed.

If you did generate the bill and can't reprint you can either undo and redo or create a history bill with the appropriate parameters.