i wanted to open Windows Explorer but it came out in prompt

[nahamayo0]

I encountered an issue with my Windows 7 operating system. After logging in i wanted to open Windows Explorer, but it launched as a Command Prompt window instead. all the icons for my desktop programs have changed to the Command Prompt icon. This change occurred after i tried to run or install a program using the Windows Command Prompt. Can you assist me in resolving this problem? Thank you!