I'm sorry to hear that you're having this issue.
Just to clarify, is the problem you're having related to the DirecTV remote, the Samsung remote, or both?
If it's just the DirecTV remote, it may have reset (?) and there is an online guide that they have that helps you program your remote. Try this link and look at the FAQs on the right hand column:
My Samsung (LN40A53OPIFXZA) recently stopped allowing me to turn tv on or off via remote. It still blinks and lights on remote and tv, but tv doesn't respond. The receiver button works fine though.
I have been using the Direct TV remote to turn tv on and off but Direct TV prompted to program remote codes and all of a sudden I can't get any picture or sound.
Anyone else hear about this issue?
Any advice is appreciated.