My PC was having problems and lightroom wont not open, so i backed up my lightroom catalog and all the backups,
Reformed C: drive reinstalled Win10 and reinstalled Lightroom 5.7.1
now it wont open my ligthroom catalog or any of the backup files
says everything corrupt or can not open.
More than likely, there is no solution.
Sometimes, one of the Adobe staff who frequents this forum offers to take a look at your catalog and see if it can be repaired.
But if your catalog and all the backups were on a disk that is failing (which sounds like the situation you are now in), reformatting the disk won't help, it's still failing. Backups must go on a different physical drive than the originals, then if one drive fails, the backups are still good.