I am unable to start the emclient after I did an export of old emails to eml. It won’t start from the start menu, the tool bar, or from clicking the .exe file in the Program Files folder.
I need to update to the newest version, so should I just download a the latest version from the website and install?
Have you checked the Task Manager to determine if there is already an instance of eM Client active? If you find one then End that instance, try starting again.
Yes, you can try that. It is something I usually overlook and can be a simple fix. 
Otherwise uninstall eM Client, making sure NOT to delete the database folder when asked. That will ensure all your settings and data are still there later on.
If it exists, delete C:\Program Files (x86)\eM Client\
Download and install the latest version from the Release History