There are basically four parts to almost any toilet. The first and the largest would be the toilet bowl and this is the area that you will be depositing your waste directly into, the next will be the toilet tank which is the area that holds the water, before the toilet is flushed and is usually located on top of the toilet bowl.
Then we have the toilet seat which is the part of the toilet that you actually sit on, while making your deposits into the toilet. The last part of the toilet, besides all of the movable components that are located within the tank, will be the tank lid.
It's not uncommon to find a damaged tank lid. The biggest problem becomes finding a replacement. There is more than one way to damage one of these lids and once they are damaged, there is a good chance that you will need to replace the entire toilet.
It's often hard to find an exact toilet lid replacement. However, sometimes you can actually replace the toilet tank and save yourself a couple of dollars. If you're toilet lid is cracked, I recommend taking a damaged item down to your local home improvement center or plumbing supply warehouse to find a replacement.
You might need to buy the entire toilet tanks, even if you do not need a new tank. These toilet tank lids often are not sold separately. I would recommend purchasing the toilet tank and storing in safely, just in case you're toilet tank ever has problems.
Hopefully you will never need to replace the tank, however it would provide you or your family and friends with a spare tank if needed.