I've noticed every weekend that someone buys a copy of The Vampire's Salvation! It's ranked 35000 Kindle edition in the UK and 214,912 for kindle in the US. That doesn't mean that I will be rich anytime soon. However it is a rise from nothing at all. I think one of the main reasons is because I changed the cover. If you don't have a good cover it will be hard to capture any audience. An author I talked to from the UK was sure the reason his books weren't selling well was due to him being of color. However, after looking at his cover, I told him he had the wrong C word. It wasn't his race, it was his book cover. Your book cover is the first thing people will see. You don't have to pay people hundreds of dollars to get a good book cover. I purchased Print Artist Platinum 23, and made my own covers for The e-book format on The Vampire's Salvation and The Torn Veil. I'm in the process of changing my cover for Luck of the Curse. The program which I got from Best Buy was $45.00.
If you aren't selling anything and you have been out for months. It's time to look at your book. Go back and look at your formatting, cover, and your grammar. Above all don't be afraid to go back and change things. If you find a mishap fix it. I go over my books all the time, so I am continually fixing things.
As a self published author you have one thing going for you that some others might not have. You have the power to correct problems right away. Don't beat yourself up if you find something. Some of the most popular traditional authors have had their share of grammar slips. Don't fear time.