what are the best way to recover corrupt data after the server went down?
How have you determined there's data corruption? Did you run DBCC CHECKDB?
If you haven't yet, run it on your databases and post the output here. DO NOT attempt a repair until someone can look at the output.
Here's some articles on database corruption:
Also, what is the situation with your database backups? How often do you back up the database and transaction log, and when was the last backup before the server crashed?
There can be different reasons for corruption as hardware failure, virus attack, power failure, etc. So to check it there is an inbuilt solution for overcoming the situation of corrupt MDF File, You can use by checking it DBCC CheckDB to check the status of corruption.