If there are not important files on the hard drive, you can repartition it. During partitioning a hard disk, you can select partition table type, partition numbers, sizes, etc. After that, you’ll be able to get a valid partition table. If you do not try repartitioning, you can try rebuilding MBR using an installation disc. You can refer steps here to rebuild MBR manually:eassos.com/how-to/how-to-fix-invalid-partition-table.php