Hello my name is Laura, Why does my toilet sound like a fog horn after I flush it.

Hi Laura,
Some thing's vibrating insude your ballcock. If you have a float ball filln valve then shut the water off to the toiulet and unscrew the three top screws band pull the float ball and washer assembly up and out. Reverse the washer and seast it in firmly. Now place a pan over the open valve and turn the water back on for a moment to flush out the supply. Reassemble and give it a flush. Noise better now? Good luck, Tom