1) Sometimes the screws used to fix the handle to the door have been over-tightened, especially if an electric screwdriver has been used. Over-tightening can cause 2 problems.First, this causes the backplate on which the handle is mounted to 'pinch' into the door and in turn 'pinch' the lock\/latch, stopping the spring inside the lock\/latch from doing its job properly.Secondly, over-tightening can create friction on the spring which is inside the handle backplate. To rectify these issues just loosen each of the screws that hold the handle very slightly (say a quarter of a turn to each screw). Try the handle, and if necessary loosen the screws a bit more.2) Many hollow stainless steel lever door handle have internal springs which, if not properly lubricated, can grind against the inners of the handle backplate.To check if this is the cause of your problem, do the following. Remove the handle from the door. Hold the backplate in one hand and operate the lever with your other hand to see if it appears to be grinding, If it is, smear a little grease or petroleum jelly onto the spring and move the handle a few times until the grease\/jelly has worked its way into the spring mechanism.The handle should now move freely and can be re-fitted to the door.3) Some door handles have a long 'neck' on the inside where the square spindle bar locates. Occasionally these can bind against the door, preventing the handle from returning to its normal position.Remove the handle from the door and lay it flat on a table. It should rest flat but if it 'rocks', then the 'neck' is protruding further than the handle backplate.You will need to drill a hole in each side of your door big enough and deep enough to allow the handle backplate to rest flat against the door.