I can't solve the mystery of where your betta is but have you looked down the back of the tank and inside the filter?
Your stocking is actually a bit of a nightmare
1 enf
5 clown barbs
4 neon tetra
2 algae eaters
3 silver sharks
3 guppies
2 angels
You should
never keep bettas and angels together, as they will kill each other (it's not a matter of
if, it's a matter of
when).
I'm not sure what an enf is, or clown barbs, but if they're anything like tiger barbs you've got a huge potential problem there - according to more than one website "clown barbs should never be kept with delicate finned fish like angelfish". I would assume that would be even more true of bettas.
Guppies and bettas don't mix, but that's largely because the betta will attack the guppies, mistaking them for small male bettas.
You don't say what species your algae eaters are, but if they're Chinese Algae Eaters, watch out as they are extremely aggressive, extremely territorial and don't even eat much algae as adults, prefering their tank-mates eyeballs and slime coats.
Neons are the natural diet of angelfish, which is presumably the reason you've only got 4 left.
Silver sharks are schooling fish and can grow to 12" long, requiring the largest of tanks to keep them happy.
You will need to take some fish back to the LFS and have a serious think about your current mix of fish. If you could tell us the size of your tank and which fish you are most keen to keep, we could probably guide you in sorting it all out.
Also, check your tank is properly cycled by testing your water for ammonia and nitrite. If you aren't sure about the science behind cycling, have a read of the article in my sig. Good luck.
i have looked everywhere in the tank but no sign.....If he had been attacked surley i would of found a body 
i just can't see how he can just vanish 
