The first thing to do is to get yourself an external 2.5" caddy, like click here
You could then plug the caddy into a separate computer and retrieve the data.
Once you have your important data, you can assess the problem.
If the laptop is less than 1 year old,put the hard drive back in and return the computer get it fixed.
If it is over 1 year and you have no warranty. Then you will have to assess the condition of the hard drive. It maybe just a problem with the MBR, in which case a reinstall from the recovery disk may put it back to normal
It could be that the hard disk has given up the ghost and died.
it could be just the connections on the end of the hard drive. In which case, re-inserting the hard drive may cure the problem.