I was thinking about your problem this morning as I wasn't sure how to help you.
My suggestion is this;
Uninstall Evernote Using the Revo Uninstaller Once Again.
Before Trying to Reinstall Evernote, Run a "Disc Cleanup". You can find this by going to Start Menu > Accessories > System Tools. Basically this should make sure to delete all of your Temporary Files so that the old install files are completely flushed. (Or so I think)
Also do a search in your windows explorer for Evernote, and delete anything you find that is related to the previous install.
Once you've ran the disc cleanup and checked for any files you may have missed, make sure to completely shut down and restart your computer.
Lastly, download the most recent version of Evernote from the site, and when you run the install for the new Evernote, make sure to customize where the new installation is being put. Make sure your install is in your "Program Files" folder.
If that doesn't fix the issue, then I would do as the previous member stated:
In the meantime if you need to get to your notes, use the web application as that should still work and have synced all of your notes.
Hope that helps. Best of Luck to you!