I hope you ran that dd command so that "corrupted.disk" went to a different physical drive.
Regardless, do not do anything to that drive that could cause a write. If the OS is on there, then do not boot it. Mount the drive in another computer such that you control any use of it. (Or simply boot the current computer from a different physical drive.
One standard advice is to first clone the problem drive. If that "corrupted.disk" file is on another drive, then you have done this. BUT---check to be sure the file is the right size. It should be equal to the total capacity of the drive, regardless of how it is partitioned, or what data is on it.
In addition to testdisk, the other standard tool is photorec (both from the same author)
Not really relevant, but writing to partition as you describe should not affect the MBR.