I lost one important file and have been happy that Recuva could found this file and it was not marked as overwritten. I am currently using the free download.
So great I clicked recover, but it said "1 partly recovered file".
the file is back to my second drive. While opening It seems to be damaged.
now I have seen that the professional version has advanced function to recover.
Before purchasing, is there a good chance that this will help?
No, purchasing Recuva will not make any impact on this.
We don't 'cripple', or artificially limit, the main functionality of our software, so the scanning and recovery process is precisely the same among all editions of Recuva.
(Purchasing instead would provide access to priority tech support, automatic updates, and the ability to create a .VHD 'image' of the affected hard drive to prevent changes from affecting the data you're trying to recover, as well as allowing the software to scan such .VHD files.)
In short, the reason Recuva cannot repair files, it can only recover them exactly as written on the disk at the time of recovery. Unfortunately, if the file is already damaged, that means that it will be recovered damaged.