My digital camera won't allow me to take pictures with the SD card in, what do i do?

I have a nikon somthing 300 or something i don't know, well when I first got it I charged it up&used it right away, well when I went2import my pictures like a bonehead I realized I had taken pics without the card. So I erased all the pics put the sd card back in&now whenever I try2take a pic it say "memory card is Write protected"what does that even mean&how can I fix it? It sucks because the camera&the card are brand-new, but when I take the card out it takes pic like no problem its really annoying please help

Check the side of the SD card for a sliding lock, it's usually grey and very small.

There's a little swith on the card. That is the write protection. Turn it off

The memory card has a little slider on the left hand side. It needs to be positioned at the top (ie the contact end of the card)

You seem to be incorrectly erasing/deleting the files from your memory card. Deleting them via the computer or using the 'delete all' option in your camera, is not really a good way to delete all files.
After you check the sliding 'Lock' switch on the side of the card, put the card back in the camera, then go into the Menu and find… Format. Do a format every time you need to delete all files from the card.