Since the official desktop app no longer supports Windows 7, WhatsApp Web is the most reliable and secure way to access your chats without installing potentially unsafe third-party software.
If you require features not available on Web (like some calling options) and cannot upgrade your OS, you can use an to run the mobile version of WhatsApp on your PC. How to Install WhatsApp on PC [Windows 7/8/10] download app whatsapp for pc windows 7
Use your phone to scan the QR code displayed on your computer screen. Since the official desktop app no longer supports
Your chats will sync automatically, allowing you to send messages, photos, and documents from your Windows 7 desktop. 2. Using an Android Emulator (Alternative) allowing you to send messages