Command prompt is not working ?

                                                        Method 1. 

Update PATH  to enable CMD

1. Click home button and search Environment Variable. 
2. Then select Edit the System Environment Variables.
3. Open Advanced tab in System Properties. 
4. Click the Environment Variables.
5. Click PATH in Environment Variables and click on Edition 
6. Make a new entry and add C:WindowsSysWow64, then click OK.
7. Reboot your system and start your CMD

                                                            Method 2. 

Try System Restore to fix Windows 10 Command Prompt not working 

1. Click Start and type: System Restore in the Search box.
2. Click System Restore and then select a recent restore point that you’ve created, click Next.
3. It will Take some time to  restore, after restoration your CMD issue will resolve