Answer:
I am what bring things together. Without me everything you see would be a total mass or debris everywhere.
I have a foot but no leg. What am I?
Taken from a mine and then locked up in a wooden case. I am used by students everyday.
I am black and white. I have strings I have keys. I make sound without my lips. I make dough with no flour
I am a rock group with four members. All dead one was assassinated.
I tell people to be careful when handling boxes.