It may be possible to close the gap utilizing retainers. If you no longer have your retainers, new ones can be made and through a limited treatment process your orthodontist could make adjustments. It would be necessary to wear the retainer
full time during this stage of treatment. After completion of treatment it would be necessary to wear your retainer at night for as long as you want to maintain straight teeth. Invisalign
aligners is another option in treatment.
My best advice would be to visit a university trained orthodontist for an opinion. Since each individual case is unique an examination would be required in order to determine the proper course of treatment. If indicated, diagnostic records might be needed in order to make the correct diagnosis and treatment plan.