Choose MOBILeditFramework.exe - main executable file of MOBILedit and click the End Process button.
MOBILedit will be terminated after confirmation.
Sometimes when you close the program its does not fully halt all processes that are going on in the background. Meaning when you want to reopen the software it is unable to as it is still lying active in the background of your system. Now as the system thinks the program is already running it will not allow another window or process to run.