How do I get a new publisher for my book?

You need to see what your contract says about reversion of rights. I suspect Crow is right. You almost certainly won't be allowed to publish the book with another publisher while it's under contract to the current one, and getting out of the contract could be difficult and expensive. Many vanity presses have contracts that are distinctly author-hostile.

You probably don't want to hear this, but you might be better off regarding the book as "lost" and starting another one that you'll publish properly.

Also, I'm not a betting man, but I'd wager a not-entirely-insignificant sum that most if not all of the reviews where you didn't already know the reviewer were paid for by the publisher out of the money you paid them to market your book. If that's the case, the people who wrote the reviews didn't honestly think you're a literary genius. I doubt any of them read the book at all...

You probably can't, I'm sorry to say, since it's already been published. Very few publishers are interested in purchasing second rights, and your vanity experience used up first rights.

You can, of course, see if you can get agents or publishers interested anyway, the same way everyone else does, by identifying the right one for you and for this book, sending a query letter, and crossing your fingers. Your query letter *must* reveal that it's already published. (If you don't and they find out, your name may be blacklisted at the publisher or agency and could literally be shared among those in the business as a person who's unprofessional. Yikes!)

Consider it a very difficult lesson and start the next book. Freely borrow themes, characters, plot elements, settings, etc. from the first one if they serve you, but don't copy anything directly between the two and don't just rewrite the same book.