What do I do when I strain my voice?

ok, so yesterday I was singing really high, because on youtube i saw this video about how high soprano high C is. So I sang it and it was fine, then I saw another video of how to sing an octave above high C . I sang that and I think I strained my voice. I know your not supposed to do that because it'll ruin your voice forever. I'm a pretty strong singer but I'm afraid I'll never sing again. What do I do?