When I print photos, it doesn't show the date on the photo. Also , when I scroll down to Date/Stamp on the menu, it is always "off". And I can't change the setting. Help

Here is how mine works at least.Yours should be somewhat similar.At the bottom is how you set up date/time.
Turn on the camera.Push the MENU button.Push up on the directional pad until the options of PHOTO and SETUP are available.Push directional down once if they are already available(mine is).You should see under the options on the first screen(number 2 list on left side).Push right.Push down until you are on the date stamp option.Push right again and it should open the the options available.Scroll down and select what you want and press the FUNC OK button in the middle of the directional pad to accept.Push the MENU button to exit.

Move highlighted option at top to SETUP by using the directional pad.Push down to the correct option screen(mine is number 1) where it says SET DATE or something similar.Push right to make the SET DATE highlighted.Push right again to set the date/time.When correct info is there,press FUNC OK,or whatever yours says in the middle of the directional pad to accept it.
You may want to print this for future reference.I do not use mine so I am not sure if it keeps it updated with the batteries removed,most likely does not.You also may want to try a few for practice and examining.I had a camera once with this feature built in and I was disappointed with how much the DATE stamp interfered and/or took away from the picture's appearance.Good,luck Greg

You haven't said what make/model your camera is, so it is hard to advise.

Without knowing the camera, I am guessing that you may be in the wrong mode when trying to change this setting. You won't be able to change it while reviewing pictures already taken. You can only change it for pictures to be taken subsequently. Once pictures are taken, you won't be able to add the date stamp, nor remove it if it has been stamped.

It may be that it won't allow you to set this if you haven't already set the date and time in your camera. I can't see why this setting would be shown at all if it was not possible to turn it on (i.e. if your camera did not have this feature).