ADE 4.5

OK, so I had Adobe Digital Editions 3.0 on my laptop for a long time and it worked great. Last night it prompted me to update it to version 4.5, so I did. Now I can't get my epubs to open with it. I wanted to set it up like before, where epubs open automatically with ADE, but it doesn't even show up on my list of programs to choose from. I put version 3.0 back on and now it doesn't work either. I uninstalled everything and started over, but still no worky. No previous versions are available either. Any ideas?