Plenty of people lose friends after highschool and by the sounds of it, you're just in summer right now so when you get to college try joining some of the groups.
My brother who is very shy, depressed and etc etc was friendless going into college and now he has two close friends.
And if you were the class clown in school you should still be able to make people at work laugh and maybe you can befriend a coworker.
Don't worry so much and panic. You're like 18 you can make friends and the after highschool transition in life is always tricky and awkward. You'll be aight