No boot option in clover

Hey all!
My friend made this Hackintosh for me a while back, and it’s been running on High Sierra pretty solid. I’ve been really happy with it—until the other day when I powered it up and it wouldn’t boot
!I’m seeing the Clover menu, but there are no boot options. This is a first for me, and I’ve read everything I could find online, but I’m a total noob and a lot of it goes over my head. I can follow tutorials, though!
Could someone please help me out? I’d really appreciate it! Thanks!