It is better not to store files on the C drive. But if they ended up there during a Windows crash, after which you need to reinstall it, you can choose to install a new Windows with the files saved at the stage of choosing the installation location. In modern Windows 10 and 11, you can use the cloud reinstallation with keeping files. In these cases, the files of the old operating system will be saved in the “Windows.old” folder on partition C. But even after reinstalling Windows without saving data, the necessary files can be restored using a program like Starus Partition Recovery.