Solution 1. Try to change the battery if this not solve your problem do a remote control test using your mobile phone.
Solution 2. So, if your remote isn't working right, wake your smartphone and pop open its Camera app. Next, switch to the front-facing camera, point the remote at the camera, and press any button on the remote. If the remote is working properly, you should see a flicker of light come from the IR blaster as viewed through your phone's screen. If your remote control is transmitting signal try to factory reset your box maybe the box itself have problem not the remote control.
Solution 3. Borrow a remote from your friend that has the same unit or ship your remote to a friend that has the same unit to test if your remote control is working fine.
Solution 4. DIY repair your remote control if no one can help you. You can go to your nearest electronics technician to do it for you. If not then proceed with RISK. It might work or it can damage your remote for good.
http://www.instructables.com/id/Repair-your-remote-controls/