how to boot or access problem file system

[PJ]

What can be done to access a file system that seems to have the boot
sector screwed up?
The /usr files should be ok but how to access?
I get errors that the file system is full and I have no idea of how to
deal with the boot up - the help message is no help!
Boot says it cannot find a kernel... surely there must be some kind of
recovery process even if nothing has been backed up. Surely FreeBSD must
be have something that functions like certain software does on MS ?
I don't have a problem with irrecoverable files, I would just finally
understand how things work and what can be done on FBSD.
TIA.
PJ

-- 
Hervé Kempf: "Pour sauver la planète, sortez du capitalisme."
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Phil Jourdan --- pj at ptahhotep.com
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