My camera is saying something but i don't know what to do?

My Nikon D3100 keeps saying on the screen Memory card is locked. Slide lock to "write" position.

i'm not so sure on what to do, all i did was put the memory card back in, it was working and didn't say this until now.

Look at the memory card. There will be a little slide switch along one edge. That needs to be moved to an unlocked position.

On the side of your memory card there's a little tab that needs to be slid in the opposite direction than what it is in now.

That is because that is exactly the problem and Nikon gave you the solution.

Slide the lock on the card to the unlock position.

Someone, maybe even your, set the lock/unlock switch on the memory card to unlock

I have a Nikon D3100 and as soon as I turn it on it says memory card cannot be used. It does this even when I put a brand new sd in it. Any help ti get past this?

I have a Nikon D3100 and when I turn it on a message pops up say this memory card is bad. It does this even when I put a brand new sd card in it. It won't let me get past this message. Any suggestions?