If you can start the program do a program reset - File Settings, Reset program to defaults.
Failing that using Wondows Explorer search for videodeluxe.ini or movieeditpro.ini depending on which version of MEP you have, include hidden folders in the search. You will find several versions of this file - delete the file that is the largest in size ( ~12 - 25 kb in size) and then start MEP.
If that fails come back with more information as suggested inthe post referred to above.
Re-installing rarely fixes problems if you do not use the Magix Cleanup tool to remove remnants of the software left behind.