I have an inability to move right wrist backwards and numbness in my fingers after leaning on my elbow for a long period of time while working ?

Nerve compression: It sounds like you are experiencing compression of one of the branches of the radial nerve or vascular compromise due to positional changes. This can be at a variety of different levels other than just the elbow and so your shoulder and spine should be evaluated as well.

Couple things: Limited wrist motion is likely related to wrist issue, but numbness in the hand with elbow posturing is likely nerve related. Best to be seen and evaluated by an orthopaedic or hand specialist, and further test are likely needed.