First, try myisamchk -r -q tbl_name ( -r -q means “quick recovery mode”). This attempts to repair the index file without touching the data file. If the data file contains everything that it should and the delete links point at the correct locations within the data file, this should work, and the table is fixed.

https://dev.mysql.com/doc/refman/5.7/en/myisam-repair.html#:~:text=First%2C%20try%20myisamchk%20%2Dr%20%2D,and%20the%20table%20is%20fixed .