You have an overloaded inbox, many messages need replying to, many need reading, and many just need filing. This is where Flagging your mail can come in handy.
Go through the messages in your inbox and for each message that requires action or you need to reply to it, flag it. This will display a neat red flag icon next to the message, making it easy to spot when scrolling.
While you are at it, set up a smart folder in your mailbox which displays all of your flagged messages. This will make it even easier to sort through the stacks of messages you need to get through.