How to manually fix a partition table ?
Use fdisk. Put it into sector mode with the u command, then p to print the table, d to delete the partition, and then n to recreate it. When you recreate it, use the same starting sector, but an ending sector that actually fits within the disk. When you are done and have double checked ( p again ), save and quit with w.
Download and install Boot Repair, an automated recovery tool that usually solves these kind of problems.