MS SQL 2008 Databse in Suspect mode and CHECKDB returns error: Object ID 3 has chain linkage mismatch We did a disk expansion for VM DB server. However, after this operation the DB became suspect mode and cannot be open.

Then we tried somethings like that;

https://www.sqlrecoverysoftware.net/blog/repair-database-from-suspect-mode.html

But the first CHECKDB step returned the following results:


  Msg 7987, Level 16, State 1, Line 1 System table pre-checks: Object ID
  3 has chain linkage mismatch. (1:13853247)->next = (1:446), but
  (1:446)->prev = (1:17209791). 
  
  Check statement terminated due to
  unrepairable error. DBCC results for 'myDB'. CHECKDB found 0
  allocation errors and 0 consistency errors in database 'MyDB'.


Also, we bought some data recovery tools but they can transfer some of the data, not all of it.

Are there any suggestions?
The repair is unrepairable (linkage issue in system table), so you would need to restore it from a good known backup to a point in time (provided the DB is in full recovery and you were taking log backups) you did the disk expansion.

You can try repair allow data loss as last resort.