If your .FRM file gets hosed up, you’ll need to repair it or your database(s) will be worthless. You’ll still need to make sure you make regular backups of your databases so you can use them to rebuild the .FRM file.
Get last good backup of database (assumes the backup is an .sql formatted single file).
Grep out the schema from the .sql file (grep -v ‘INSERT INTO’ [.sql file] > somefile.sql)
Locate the schema for the broken table.
Go into a mysql shell and create a new table with a different name and same schema as the broken table (located in step 3) in the affected database.
Copy the [newtable].frm file in /var/lib/mysql/[database] to the [brokentable].frm, overwriting [brokentable].frm
Remove the [newtable].MYI/.MYD files from /var/lib/mysql/[database].
Run on a count on the newly fixed table and make sure there are records.
Run a mysqldump of the database and make sure it completes successfully.
Clean up any unneeded files created in the process of the fix.