converting to MP4

I have a video.  It was sideways on the screen.  I found the only program I could use to rotate it was Windows Live Movie Maker.  I rotated it and tried to save it.  I ended up with this little movie in 6 different places because I kept trying.  I ended up with it as a .wlmp file and another on as a .wmv file.  The problem is, I can't send it or open it or anything.  I can't change it to an MP4.  I wanted to be able to attach it to a facebook message, and to an email.  The only way I can do that is to use the original MP4 file that is sideways.  I can open that with several different programs (not photoshop, though) but I can't seem to edit with any of those.  Can anyone help me?  I just want to turn this 37-second video right side up!