What is this type of damage, and is there an economic way to repair? Windows are 20 years old and unknown maker. What is an expected cost to have a window like this repaired if not feasible to DYI? Several windows like this. Some are moveable parts others are non-removable.
That looks like a sealed double glazed unit. Contact your local glazing company, and they will be able to make a new one up of the same width, height and thickness. Swapping them out isn't that difficult, but probably best left to the professionals. It usually involves prying out the beading around the edges of the glass.