Postgres eat my data suddenly...

Hi all.

I use postgres to collect all information of my work.

Debian: 3.0r1
Version: 7.2.1
Libc: 2.2.5

I have change a table schema and since this Postgres has lost the
definition of some table.

That is.

The database's name is 'dbore'. Inside I defined a table ore. The schema,
since january 2003 was

codprogetto: integer,
ore: smallint.
descrizione: text,
data:date,
id: SERIAL.

Yesterday I add three field to the table

dalle: time without timezone
alle: time without timezone
pausa: time without timezone

I have made last pg_restore in Febbrary, when I change my PC.

Since I have change the schema of 'ore' I can see only the data of the
last pg_restore.
Then if I try to SELECT on pg_class table I look two occurrence of 'ore':
one with relnatts=5 and the other with relnatts=9.

Why?

I try to add some data to the broken db but psql tell me that I'm trying
to add data the already exit in the db.
Then all data for Febbraty until today are already contained in the db.

It seems that all data added to all any managed by Postgres from March
until now can't be accessed.

How can I retrieve the missing data?

Thanks to all
Mauro