Perhaps you have a large capacity drive, or lots of files to wade through, or maybe even a failing drive and sectors have to be re-read multiple times.
In case it may help others chime in;
what OS are you running?
how was the drive formatted: FAT or NTFS?
why are you using Recuva: accidental deletion of files, corrupted drive, accidental formatting?
drive capacity?
internal or external? if external, how connected: USB, NAS etc?
The operatingsystemwill not load, attempts torestoreorhave failed.Duringreinstallwindows,it was foundthat the diskhas becomeemptywithout a singlefile.For whatever reasonthis happenedis not clear.