Firstly, is it true that somebody bad intentions can cause trouble and hindrance into others life?
How can lemon/chilli/salt/red brown or black beads worn in wrist keep us away from the evil eyesight?
It is possible but it is peripheral:
"Many times, I have been asked, what to do if someone has cast an “evil eye” on me.
The first thing to do is to not bother about it. Gurudev had once said, this is all simply on the periphery and will just vanish in no time. He said any sort of “curse” is always peripheral and will go away very fast. However, a blessing comes from deep within and will stay for a very long time!
Having said this, there are a few things you can do if you are feeling that you are the victim of an evil eye. Typically you will see that for absolutely no reason, you are being unwell, losing money, having minor accidents, friends not talking to you, etc. It could of course mean you have been in too many polluted places, too many shopping malls or are being careless and simply not being nice to people around you. However if that’s not the case, then it could be some petty jealousy of someone has rubbed off on you and you have become the victim of an “evil eye”.
Super regular Sadhana, Seva and Satsang will blow anything negative away from you! Go for a dip in the sea. Or take a full body bath with salt water few times a week. Get someone, typically an elder woman (it works great with younger ones as well) to do the nullifying the evil eye ceremony on you (Nazar uttarna). Or go to a priest you know well and ask him to do it for you...."
You can read more here: http://bawandinesh.name/the-evil-eye/
Also, lemon, chilli etc do not work. Salt does as mentioned (dip in the sea). Is is said that the salt crystals have a cleansing frequency. I am not sure if any research has been done on that.