How can I replace a sliding glass door with a broken seal?
If repairing the glass as RQDQ suggests does not pan out, you have three options:


Order replacement glass.   Typically a company that specializes in glass replacement would measure the panel, order replacement glass, and install it in the fixed or moving panel from your door.  Manufacture and shipping of the custom dual-pane glass panel may take from one to several weeks.
Order a replacement panel from your door's manufacturer.   This may or may not cost more than replacing the glass, but you will be able to replace the panel with basic DIY tools and skills.   This may not be possible if you cannot locate the original manufacturer or if an exact match is no longer available.
Replace the entire door unit.  This may be appropriate if the original door is not high quality, you want to upgrade, or perhaps if you want to change finishes (from metal-clad to wood or vinyl-clad, for example).   This will require more skill, as you will need to remove and replace trim inside and outside the door, and possibly will involve removing and replacing siding in the vicinity of the door.


In either of the last two cases, it is more than a 1-person job; be sure to have help to safely handle the removal and replacement of the panel or door unit.