HOW DO I SEARCH & BUY CORRECT SCREEN for my sa

when I search the model Off My "about phone" list, I cannot bring up ANYTHING! Im so frustrated.! Do I group my model into group? Do I know if its a J7 JT J1 JS........WHAT THE FREAK.? Off my phone it says...~~SM 120VL~~iSNT THIS WHAT i'M SUPPOSED TO BE SEARCHING FOR? Im scared to buya replacemnen t digitizer screen cuz I cracked mine, and get incorrect parts. I just need help mainly with this so I'm serching for the correct parts. I chose my device in this site as it appears above, is that what my problems is then? Do I search the category? (group?) I know about where to go, just cannot pull up my exact model. Any motivated help would be GREATLY appreciated. Thank You for your time. ang.