How much does it cost to replace a broken screen and trackpad on a MacBook Air?

Just to add a bit to John Galt's reply.

We have no idea which exact model your MacBook Air is or what the exact damage it has sustained. Since we are not Apple employees, we can't give you any official estimate on what the cost to make the needed repair. Actually, even if an Apple employee reads this post, they won't be able to provide you a quote either.

As such, you would need to take your MBA to either the Genius Bar at your local Apple Store or to an Apple Authorized Service Provider to have then examine it. That examination would be free.

And as John Galt has already mentioned, if you did not elect to get an AppleCare+ plan with this Mac, or if it has expired, the out-of-pocket cost can be substantial.

Assuming you did not purchase an AppleCare+ product (that would be Apple Care Plus), repair will cost nearly as much as a new Mac.

Don't take my word for it though. Start here: Official Apple Support