“How do you fix receding gums without surgery?”

You can't.

Non surgical correction for receding gums is difficult. First identity why the guns receded in the first place. Too stiff a toothbrush bristle? Brushing with too much force? Thin layer of bone supporting the gums? Periodontitis? The best way to prevent receding gums is to use en electric toothbrush which has a built in stress gauge which alerts the user when excessive force is being applied. This would be a great topic to discuss with a periodontist.