I don't think we can tell what you are trying to accomplish. Are you trying to restore the OS on a PC? If so, can you say something about the brand, operating system, and what media you have. If you've formatted the hard drive the operating system is on, you should get some error message to that effect if you try to boot the PC. You mentioned virus. Were you having problems causing you to suspect this? Deleting or creating a partition depends on what software you have to do such. If you have a working Windows PC, you can only delete or create partitions on another drive or free space other than the Windows OS partition. More info would be helpful.