Database curruption

Hi, 

CHECKDB found quite some errors on a database. The error messages are like:

Msg 8909, Level 16, State 1, Line 1

Table error: Object ID 0, index ID -1, partition ID 0, alloc unit ID 0 (type Unknown), page ID (1:3817323) contains an incorrect page ID in its page header. The PageId in the page header = (0:0).

Msg 8909, Level 16, State 1, Line 1

Table error: Object ID 0, index ID -1, partition ID 0, alloc unit ID 0 (type Unknown), page ID (1:3817324) contains an incorrect page ID in its page header. The PageId in the page header = (0:0).

Msg 8909, Level 16, State 1, Line 1

Table error: Object ID 0, index ID -1, partition ID 0, alloc unit ID 0 (type Unknown), page ID (1:3817325) contains an incorrect page ID in its page header. The PageId in the page header = (0:0).

Msg 8909, Level 16, State 1, Line 1

Table error: Object ID 0, index ID -1, partition ID 0, alloc unit ID 0 (type Unknown), page ID (1:3817326) contains an incorrect page ID in its page header. The PageId in the page header = (0:0).

To make things worse, I cannot find a good backup copy of the db. Any idea about repairing this would be greatly appreciated.