After entering the command prompt state, no matter what DOS commands are executed, "XX is not an internal or external command, nor a running program or batch file," as shown:
The problem is that some software has modified the value of path.
1, on the desktop to find the "Computer" icon and click the right mouse button, and in the pop-up menu select "Properties";
2, click on the left "advanced system settings";
3, in the Pop-up System Properties dialog box, click on the "Environment variable" button;
4, find the variable "Path", and click the "Edit" button;
5, modify the value of the variable "%systemroot%system32;%systemroot%system32windowspowershellv1.0", and finally click the "OK" button to end the setting;
6, restart the computer can be.