Is your current staircase unsafe?
What is wrong with your staircase?
In most cases there is probably little or nothing wrong with the staircase frame itself. It may be you are looking at the stairway project because you want to make an aesthetic improvement to your home.
If there is a problem with loose treads or risers (the steps on your stairs) the best course of action is to consult a carpentry or joinery professional about whether the staircase can be repaired. If the answer is no then there are many reputable Staircase Manufacturers and companies supplying the basic staircase frame who will be able to provide a replacement.
Assuming the structure of the staircase is sound, then you can completely transform the look and feel of them to suit your home by changing the staircase balustrade.