Try renaming the normal.mxt file in your profile and seeing what happens. You'll find the file here:
C:\Users\<your account>\AppData\Roaming\ESRI\Desktop<your Arcmap Verison>\ArcMap\Templates\Normal.mxt
Rename the file to normal.old and the fire up Arcmap. It will create a new normal.mxt. Once the application is ready, try to open your MXD again. This will at least test if your Arcmap template file has gotten corrupted.