Very strange problem. Sometimes firefox' bookmarks dissapear. May be this is connected with NTFS problems (sometimes solved by chkdsk c: /f). But the best way to recover the bookmarks is to get them again from the last firefox archive. They are in
C:\Documents and Settings\[username]\Application Data\Mozilla\Firefox\Profiles\pypbblhs.default\bookmarkbackups
and the last archive must be ranamed and put into
C:\Documents and Settings\[username]\Application Data\Mozilla\Firefox\Profiles\pypbblhs.default
This solved my problem :)
