I'm kind of new with XP so please help?

I received a message on my computer that the
System32/drivers/isapnp.sys file was corrupt or missing
and Windows wouldn't start. I tried system recovery and
the recovery disc would not read the system 32 drivers
files - unable to open. They are sending me recover
discs. I have the same computer at home and have the
file that is missing. But without knowing how to copy
that file onto the computer without a command prompt
before windows loads, I'm not sure how to get it on. Can
anyone tell me?