You may apply for naturalization on Form N-400 if you have been a resident for at least the last 5 years. However, you must be physically present in the US for at least one-half of those 5 years. Due to your absences from the US between July 28, 2006 to April 13, 2009, the earliest that you can apply for naturalization is February 2013.
Answered on Apr 30th, 2012 at 4:40 PM