Solved! i changed my harddrive do i need to put bthe shield back

Solution
Yes, it is necessary. It protects the hard drive from EMI and protects your other hardware or your case panel, depending on which way the shield faces, from the heat of the hard drive. On many drives it also protects the drive electronics from making contact with potentially conductive surfaces in the event of a drop or severe bump. Regardless, you should put it back. They put them there for a reason, not just because they like adding extra cost on to the required materials.
Yes, it is necessary. It protects the hard drive from EMI and protects your other hardware or your case panel, depending on which way the shield faces, from the heat of the hard drive. On many drives it also protects the drive electronics from making contact with potentially conductive surfaces in the event of a drop or severe bump. Regardless, you should put it back. They put them there for a reason, not just because they like adding extra cost on to the required materials.
 
Solution
The answer is still the same. You can fish for finding the answer you want by repeating the question until somebody eventually gives you the answer you desire, which they likely will because there are plenty of people out there that don't have a clue, but the fact will remain that these parts come installed FOR A REASON. They don't just like putting extra parts in there.

Not having that shield installed will allow the heat of the hard drive to directly warp the plastic of your laptop chassis if there is not a heat shield in place between the unit and the chassis. It will also leave the underbelly of the unit exposed to potential damage. It's a bad idea. Can you get away with not putting it back, probably, for a while, but again it is there for a reason and later on you will likely wish you had taken the time to pull it back out and do it right.