@Jeneenae, I have no personal experience with repairing the screen door, but these discussion threads may get you started (or at least make you aware of what is involved.) There are other discussions on this forum. Use the "Search" box at the top of the forum page and enter "screen door" or related terms to find additional info:
While it's not the simplest of tasks, it is doable and a whole lot cheaper than a new door (that is, if you can even get one these days). Study the resources for Bayliss' first link above carefully, and assemble everything you need before diving in. And feel free to post questions (or requests for emotional support) here... ;-)
Comments
https://tab-rv.vanillacommunity.com/discussion/11252/tab-400-screen-door-string-repair#latest
https://tab-rv.vanillacommunity.com/discussion/13390/help-screen-door-string-issue#latest
(Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
Greg & Marlene (Tucson, AZ)