I have solved the same problem of my iPhone, this my method:
Step 1: Disconnect the data cable and turn off your iPhone.
Step 2: Press the "Home" button and connect your iPhone to the computer with data cable, and then release the "Home" button.
Step 3: Now you have enter into recovery mode successfully.
Step 4: It is very easy for you to exit recovery mode. Please press both the "Home". button and "Power" button at the same time until the LOGO "white apple" appeared on the screen.
Hope it helps.
Step 1: Disconnect the data cable and turn off your iPhone.
Step 2: Press the "Home" button and connect your iPhone to the computer with data cable, and then release the "Home" button.
Step 3: Now you have enter into recovery mode successfully.
Step 4: It is very easy for you to exit recovery mode. Please press both the "Home". button and "Power" button at the same time until the LOGO "white apple" appeared on the screen.
Hope it helps.