Hi Himanshu

Please check below things: 

Verify Salesforce CLI Installation: Check that Salesforce CLI is installed correctly on your machine. Go to command prompt or terminal window and running the command sfdx --version. Ensure that the Salesforce CLI version is displayed.
Confirm Integration with VS Code: Ensure that the Salesforce CLI extension is installed and enabled in your Visual Studio Code (VS Code) environment. Open VS Code and go to the Extensions sidebar (Ctrl+Shift+X or View > Extensions) to search for and verify the Salesforce CLI extension is installed.
Restart VS Code: If the Salesforce CLI extension is already installed but the cloud symbol is not appearing, try restarting VS Code. 
Check Salesforce CLI Path: Verify that the Salesforce CLI executable is added to your system's PATH environment variable. To do this, you can open a command prompt or terminal window and run the command sfdx plugins --core to check if the Salesforce CLI core plugin is listed. If it is not listed, you may need to manually add the Salesforce CLI executable path to your PATH environment variable.
Update Salesforce CLI and Extensions: Ensure that you have the latest version of Salesforce CLI. You can update Salesforce CLI by running the command sfdx update in a command prompt or terminal window. 

Please mark this as best answer if this helps you 
Thanks