Suspension on my navigator

I unscrewed a bolt from the air compressor on my 1999 lincoln navigator and now the back end has dropped??? I tried putting the bolt back in but nothing.

What do I do?

It’s difficult to tell without knowing exactly what you removed, why you removed it, and other details to the story. You may have to try to find a shop that has someone experienced in the air suspensions on these Ford vehicles to figure out what happened and correct it.