The easiest way to retrieve data after reinstalling Windows is back up. If you've backed up your system before Windows reinstallation, you can easily use that to get back your access to data. If no backup is available, you'd still be able to restore data with powerful data recovery software, such as Stellar Data Recovery for Windows. It is a DIY data recovery software that helps retrieve files, folders, documents, emails, and other data from formatted or corrupted drives or computers.