Anxious about not hearing back from someone

Honestly I kinda had the same experience I texted my friend and they didn’t respond for days I thought to my self “well this is it there not my friend anymore” it’s a pretty normal thing for me most of my friends last a semester long at most anyway after a couple of days I tried texting them again and they said they just didn’t see the notification and my mind went to the worst case scenario as it always does but it’s still is at the worst possible outcome always, all I did is try to forget about them not Texting back and waited to see if they would idk if or how this help it just reminded me of this