This is usually an issue of parental controls. If parental controls are on, it can cause the input to be blocked. Usually, inputing code 0000 should allow you to access the parental controls. However since you say it is greyed out you might want to try power cycling the TV:
Turn it off & unplug it, then after 30 seconds, power it back on. Then reset to factory settings. You may also try to check if the ports are functional, by unplugging each device from each port one at a time, try different ports, and then re-plug them back in. If none of this fixes the issue, then I would recommend calling for further assistance or getting a replacement.