Let’s Learn Computers!
A file that has not been saved somewhere cannot later be restored – there is nothing to restore if there wasn’t a file in the first place. It’s kind of like walking into a bank, setting a $100 bill on fire, and then asking the cashier to “restore” your $100, only the bill you burned in the first place was Monopoly Money.
Sending big files to old plotters to be printed on over-sized paper will result in long plot times. This it not something that can be “fixed” – short of buying a whole new plotter. So be prepared to wait a few minutes.