Depends upon the material and quality of the door. It could be anywhere from $1000 to $4000 to replace the whole door. Maybe $200-$300 to make a cheap repair. You'll have to get an estimate from an on-site estimator.

I have a back sliding door in my house and it completely needs to be redone this building was built in 1976 and it's a wood sliding door so the part where the metal sits in is completely stripped door falls off everytime I try to close it! Was wondering how much that normally cost?!