There are few options for reading your books on a PC or Mac - with more options becoming available all the time. In 2013, Mac users got iBooks for Mac which made the whole process a lot easier (if you have a Mac!).
As of June 2015, you can now download Book Creator for Windows and use that to view your books (requires Windows 8.1 or higher).
Other options, such as using Adobe Digital Editions, can produce variable results. We're going to focus on using Readium, an open source project which aims to enable viewing of ePubs on any device. This seems to be one of the most reliable methods, although please note Readium is still in beta and there may still be issues with reading your book this way, which are out of control.
First, you'll need to transfer your book to your computer using any method you choose - email, cloud service or send to iTunes will work fine.
Google Chrome and Readium:
1. Install Google Chrome
First you need to install the Google Chrome web browser, go to – www.google.com/chrome.
2. Install the Readium app
Readium is an app for Google Chrome that can display ePub files including those made by Book Creator.
Open Google Chrome and visit the Google app store to install Readium.
3. Add your books to Readium
Once installed, open Readium and click on the + icon to upload your ePub file from your computer.
Alternative: export the book as a video
We've detailed how you can export your book as a video file, which makes it possible to "read" on almost any device.
From the blog: