All is not lost! The grain should be settled at the bottom of the fermenter. Assuming you have another vessel about the same volume as your fermenter (like your boil kettle), sanitize that vessel and rack / transfer the wort to there using your autosiphon from the top of the fermenter. Then clean and sanitize your fermenter and transfer the wort back in. Pitch your yeast if you have not done so already. As long as everything is sanitized and fermentation has not started up, (your brew day was today), you should be fine.