how to "undo"

[bugreport19621012 at fastmail.fm]

Is there a way to "undo" my recent actions?  Somehow I seem to have deleted a reconciled transaction.  I was not aware of any dialog box cautioning me; the transaction just disappeared. I know it was there earlier because it was already reconciled in my checking account. It was about to be reconciled in the credit card account; I got distracted and "whoops!" it was gone. Is there a way to step backward, undo-ing recent actions?

Alternatively, how does one *properly* use the backup files?  My GnuCash backup directory contains several files created in the previous sixty minutes, named *.gnucash and *.log.

But if I open an earlier *gnucash file, is not my current GnuCash state lost? It seems that would wreak havoc.

Details: GnuCash 2.4.11

Thanks for any insight

Jacob Wegelin