Shower help

[Ronald182636]

we recently moved into our house and are having problems with the shower. The knob broke off and I am unsure of a replacement for it. I purchased 3 different ones but none fit. I’m very much a novice at this. Just need to know which knob I would need to replace it with. Preferably one that won’t break after 3 uses . Attached pictures below of valve and knob. Knob was removed with an Allen wrench . All the ones I purchased had a screw you screwed into valve, this one the screw presses itself against stem to hold it in place.

Thank you

 

[FishScreener]

It’s a Delta unit. that should make it easier.