how do i use windows to unlock my iphone

Assuming a forgotten passcode or disabled, see these links:

If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Locate and view your connected device on your computer - Apple Support

If seeking to unlock Activation Lock? You’ll need access to the Apple ID and password, original purchase receipts with serial number and matching photo ID, or legal paperwork.

If you mean a Windows computer, hit needs to have iTunes installed.