It started with a regular guy that saw a girl in danger of being mugged or raped or something, and when he tried to save her, the attacker shot him and he died. Somehow he got revived and discovered a magical world beyond this one, with fairies and stuff. He also had some kind of special powers, but I'm not sure what, telekinesis maybe or shapeshifting?
Also, there was an adventure in this world where he had to rescue someone from a cave or fortress inhabited by trolls and one of the trolls was a really funny guy.
There was also a big and important mansion in the story, which served as the good guys' base of operations.
I don't remember much more about it, but it was set in the present day, and some of the action also took place in our everyday world, at a concert where either the light or loud sounds harmed the evil creatures, which I don't remember exactly what they were.
The author put the first book on some "free online reading" sites, and at the end of his book asked the readers to e-mail him if they wanted to read the next book, which I did, but I lost that e-mail account many years ago.
The author's first name might have been Charles.
The book was pretty funny and lighthearted, possibly a young adults novel.