i need to know will the nail grow back (becuase it looks and feels wierd) and what chemicals or working conditions can cause this, has this happend to anyone else?
I've lost both big toe nails through playing football: it was uncomfortable but they grew back fine. This was due to me wearing boots that were too small. I would be very worried about your working conditions if were loosing nails at work. Do you not fill out COSHH forms? Your employers are leagally bound to supply you with safety equipment as well as informing you of any potentail threat to your safety. Any chemical would have to be pretty severe to cause you to loose a nail!
I agree with j2buttonsw about the safety implications. If your nail has simply come off without a knock or bang then I would suggest that you see a Doctor.